fix: heal migration-ledger mismatch and make Azure SSO deploy-proof (#18)

PocketBase on Labs crash-looped since the SSO deploy (PR #17): mounting
--migrationsDir for the first time replayed the entire migration history
against a database that was provisioned out-of-band (empty _migrations
ledger) and died on 1778948471_created_content.js. On top of that the
team_members->auth migration had its own crash paths and trapped OAuth2
config inside a one-shot, env-dependent migration.

- pb_migrations/1000000000_baseline_ledger_sync.js: detects an
  out-of-band provisioned DB (schema exists, ledger empty) and marks the
  79 historical migrations as applied; no-op on fresh or already-synced DBs
- pb_migrations/1781000000_team_members_to_auth.js: idempotency guard,
  relation->text conversion WITH data preservation (PocketBase diffs
  fields by id, so the column is backed up and restored via SQL), unique
  index rebuild, no silent catches, env only as fast-path
- pb_hooks/entra_oidc.pb.js + pb_hooks/utils.js: reconcile the Entra OIDC
  provider from ENTRA_* env on every bootstrap + cron tick
  (compare-before-save, warn-once); heals environments that migrated
  without secrets and supports secret rotation without re-apply
- pb_hooks/team_members.pb.js: require() pattern — JSVM runs callbacks as
  isolated programs, top-level helpers are not in scope (adopts Leroy's
  fix from the fix-sso branch)
- infra/*/site/deploy-playbook.yml: health-gate after compose up — the
  deploy fails loudly with container logs when PocketBase does not become
  healthy (runs #83-#88 were green while PB crash-looped)
- docker-compose.yml: .env.local is optional again
- docs/auth-spec.md + AI_AGENT.md: ledger/reconciler documentation, ADRs
  006-008, never-rename-applied-migrations warning

Verified locally against PocketBase v0.30.4 with a 7-scenario DoD matrix
(fresh DB +/- env, out-of-band DB with data incl. data preservation,
populated-ledger upgrade, late-secrets healing, re-run guard, hook
provisioning): 15/15 pass. npm test 112/112.

Closes #18

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

pb_hooks/team_members.pb.js

@@ -15,17 +15,16 @@
 // The allow-list is a comma-separated list of e-mail addresses, e.g.:
 //   ENTRA_ADMIN_EMAILS=rve@respellion.nl,admin@respellion.nl
 //
-// Keep this logic in sync with src/lib/azureAuth.js (resolveRole / parseAdminEmails),
-// which carries the canonical, unit-tested version for the frontend/tests.
-
-function resolveRole(email) {
-  const raw = ($os.getenv("ENTRA_ADMIN_EMAILS") || "").toLowerCase();
-  const allow = raw.split(",").map(function (s) { return s.trim(); }).filter(Boolean);
-  return allow.indexOf((email || "").toLowerCase()) !== -1 ? "admin" : "user";
-}
+// resolveRole itself lives in pb_hooks/utils.js and is pulled in per-callback
+// via require() — PocketBase's JSVM runs each hook callback below as its own
+// isolated program, so a shared top-level function here would not be in scope
+// at call time. See pb_hooks/utils.js for details. Keep the logic in sync with
+// src/lib/azureAuth.js (resolveRole / parseAdminEmails), which carries the
+// canonical, unit-tested version for the frontend/tests.
 
 // On creation (first login): set defaults before the record is persisted.
 onRecordCreate(function (e) {
+  const { resolveRole } = require(`${__hooks}/utils.js`);
   const email = e.record.get("email") || "";
 
   e.record.set("role", resolveRole(email));
@@ -45,6 +44,7 @@ onRecordCreate(function (e) {
 // On every successful auth (incl. OIDC): keep the admin role in sync with the
 // allow-list, so promoting/demoting an admin only requires an env change.
 onRecordAuthRequest(function (e) {
+  const { resolveRole } = require(`${__hooks}/utils.js`);
   const email = e.record.get("email") || "";
   const want = resolveRole(email);
   if (e.record.get("role") !== want) {