Remove Supabase

The database moved to a container of our own; the platform is gone.
This takes out what was left of it — and, where the leftovers were load
bearing, moves rather than deletes.

Moved, not deleted:

  supabase/migrations/  -> db/migrations/      the schema's source of truth
  supabase/build-org.ts -> scripts/build-org.ts
  lib/supabase/types.ts -> lib/types.ts        52 import sites repointed

The bookkeeping needed care. It lived in `supabase_migrations.schema_migrations`,
and simply renaming the schema would have left the runner facing an empty
table: it would have called all 67 migrations pending and replayed them
against a database that is long since current. So the runner now creates
`migrationen.schema_migrations` and, once, copies the old rows across —
guarded so a second run does nothing and a fresh database skips it entirely.
Only then does migration 20260907100000 drop the old schema.

Deleted: the CLI config, the seed, the historical schema/function dumps
(nothing read them), scripts/umzug-von-supabase.sh (the move is done), and
both Supabase packages plus the CLI. Nothing in the application imported
them — the build now succeeds with no environment variables at all, which
is the proof.

Integration tests: six of them signed in through Supabase Auth and asserted
against the anon key and the service role. That model is gone, so the tests
were not portable — they are deleted. session-context and
employee-status-filter already ran on pg and are untouched; om-reporting is
ported to a direct connection because it guards a real risk (the reporting
line rule exists twice, once in SQL and once in TypeScript).

CI: the integration job started a Supabase stack. It now runs a postgres
service, applies deploy/db-init and every migration to an empty database —
that was the valuable part, and it still holds — then checks that a second
run is a no-op, which is what proves the bookkeeping works.

Docs: security-review.md audited a service-role key, a cookie adapter and
auth.users, none of which exist. Restating findings about removed components
would suggest today's system had been reviewed; it has not. It now records
what was removed and says a fresh review is due. data-model.md was already
marked obsolete and described the pre-OM schema; azure-migration.md was a
plan for a route not taken. Both deleted.

Verified: npm ci, typecheck, lint, 445 tests, build — all clean without the
packages. Integration tests skip cleanly with no database. Migration SQL and
the runner are reviewed but NOT executed: no Docker here, and the old
instance no longer resolves.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

db/migrations/20260724120000_employee_assignment_history.sql

@@ -0,0 +1,120 @@
+-- Org-assignment history, so the Organigramm can be shown as of any date.
+--
+-- Until now `employees` carried only the *current* placement (manager_id,
+-- team_id, division_id, job_title, is_lead, org_level) and every mutation
+-- overwrote it in place. employee_history recorded that something happened,
+-- but only as free text — no old/new values — so a past reporting line was
+-- gone for good. Forward-looking dates already worked (pending_org_changes
+-- holds not-yet-due changes structurally); it was the past that could not be
+-- reconstructed. This migration adds the missing timeline.
+--
+-- Captured by a trigger rather than by editing the mutating RPCs: there are
+-- ~70 `update employees` statements spread over fifteen migrations (several
+-- of which redefine the same function repeatedly), so per-RPC bookkeeping
+-- would miss paths today and again with every future RPC. A trigger on the
+-- table catches all of them, including ones not written yet.
+
+create table employee_assignments (
+  id uuid primary key default gen_random_uuid(),
+  employee_id uuid not null references employees(id) on delete cascade,
+  manager_id uuid references employees(id) on delete set null,
+  team_id uuid references teams(id),
+  division_id uuid not null references divisions(id),
+  job_title text not null,
+  is_lead boolean not null default false,
+  org_level int not null,
+  valid_from date not null,
+  -- Exclusive upper bound; null means "still in force". Note this tracks
+  -- *placement*, not employment: the row of someone who has left stays open,
+  -- because whether they were employed on a given date is derived separately
+  -- from entry/exit/karenz dates. Keeping the two apart is what lets a
+  -- rehire reuse the same open row instead of needing it reopened.
+  valid_to date,
+  created_at timestamptz not null default now(),
+  constraint chk_assignment_range check (valid_to is null or valid_to > valid_from)
+);
+
+create index on employee_assignments (employee_id, valid_from desc);
+create index on employee_assignments (valid_from);
+-- At most one open interval per employee — the invariant the trigger relies
+-- on when it looks up "the current row" to close.
+create unique index employee_assignments_one_open on employee_assignments (employee_id) where valid_to is null;
+
+alter table employee_assignments enable row level security;
+create policy "employee_assignments_hr_read" on employee_assignments for select using (is_hr_user());
+
+-- ── Backfill ───────────────────────────────────────────────────────
+-- One open interval per employee, starting at their entry date, holding
+-- today's placement. Changes made *before* this migration are not
+-- recoverable — employee_history never stored structured old values — so a
+-- Stichtag before today's date shows the placement as it stands now for
+-- anyone whose assignment predates this table. Everything from here on is
+-- exact.
+insert into employee_assignments (employee_id, manager_id, team_id, division_id, job_title, is_lead, org_level, valid_from)
+select id, manager_id, team_id, division_id, job_title, is_lead, org_level, entry_date
+from employees;
+
+-- ── Trigger ────────────────────────────────────────────────────────
+-- The date a change takes effect is normally the day it is written: an RPC
+-- with a future effective date does not touch `employees` at all (it queues
+-- into pending_org_changes, and apply_due_pending_changes writes it on the
+-- due date), and one dated today writes immediately. A *backdated* change is
+-- the exception — it writes immediately although it should take effect
+-- earlier — so callers may set `app.effective_date` for the transaction to
+-- say so explicitly; unset, it falls back to the current date.
+create or replace function fn_track_employee_assignment()
+returns trigger
+language plpgsql
+security definer
+set search_path = public
+as $$
+declare
+  v_date date := coalesce(nullif(current_setting('app.effective_date', true), '')::date, current_date);
+  v_open_from date;
+begin
+  if tg_op = 'INSERT' then
+    insert into employee_assignments (employee_id, manager_id, team_id, division_id, job_title, is_lead, org_level, valid_from)
+      values (new.id, new.manager_id, new.team_id, new.division_id, new.job_title, new.is_lead, new.org_level,
+              coalesce(new.entry_date, v_date));
+    return new;
+  end if;
+
+  if new.manager_id is not distinct from old.manager_id
+     and new.team_id is not distinct from old.team_id
+     and new.division_id is not distinct from old.division_id
+     and new.job_title is not distinct from old.job_title
+     and new.is_lead is not distinct from old.is_lead
+     and new.org_level is not distinct from old.org_level then
+    return new;
+  end if;
+
+  select valid_from into v_open_from
+    from employee_assignments where employee_id = new.id and valid_to is null;
+
+  if v_open_from is null then
+    insert into employee_assignments (employee_id, manager_id, team_id, division_id, job_title, is_lead, org_level, valid_from)
+      values (new.id, new.manager_id, new.team_id, new.division_id, new.job_title, new.is_lead, new.org_level, v_date);
+  elsif v_date <= v_open_from then
+    -- Two changes on the same day (or a backdate landing inside the open
+    -- interval): overwrite in place, so no zero-length or inverted interval
+    -- is ever stored.
+    update employee_assignments
+      set manager_id = new.manager_id, team_id = new.team_id, division_id = new.division_id,
+          job_title = new.job_title, is_lead = new.is_lead, org_level = new.org_level
+      where employee_id = new.id and valid_to is null;
+  else
+    update employee_assignments set valid_to = v_date where employee_id = new.id and valid_to is null;
+    insert into employee_assignments (employee_id, manager_id, team_id, division_id, job_title, is_lead, org_level, valid_from)
+      values (new.id, new.manager_id, new.team_id, new.division_id, new.job_title, new.is_lead, new.org_level, v_date);
+  end if;
+
+  return new;
+end;
+$$;
+
+drop trigger if exists trg_track_employee_assignment on employees;
+create trigger trg_track_employee_assignment
+after insert or update on employees
+for each row execute function fn_track_employee_assignment();
+
+grant all on table employee_assignments to anon, authenticated, service_role;