Wire schema v1 into a manual Supabase migration and vendor the real stack

- Move db/schema.sql to supabase/migrations/ as the first supabase CLI
  migration (manual `db push` only, no automated runner); re-add the
  gebos_ingest role + grants there since init.sql never re-runs
- Add gebos-postgres-passwords oneshot on db-host: syncs role passwords
  from sops (LoadCredential, journal-safe), makes supabase_admin
  SUPERUSER and hands the auth schema to supabase_auth_admin to match
  the upstream supabase/postgres image; add pg_hba rule for 10.0.0.0/8
- Vendor the official docker-compose (studio/kong/auth/rest/meta only,
  external Postgres, loopback Studio with no Kong dashboard route) plus
  kong.yml (trimmed) and kong-entrypoint.sh (verbatim); tested: compose
  config, Kong config parse, migration applied on TimescaleDB pg17
- Document decisions as ADRs 0001-0004 (migrations, passwords, vendored
  stack, JWT API keys incl. verify/mint procedure)

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

nix/hosts/db-host.nix

@@ -8,6 +8,11 @@
   networking.hostName = "db-host";
 
   services.gebos.secrets.postgresAdmin = true;
+  # The gebos-postgres-passwords oneshot (gebos-postgres.nix) also syncs the
+  # shared Supabase service-role password and the ingester's password, so
+  # db-host needs those keys rendered into its env file too.
+  services.gebos.secrets.supabase = true;
+  services.gebos.secrets.ingester = true;
 
   services.gebos.postgres = {
     enable = true;