fix(auth): bootstrap init_db on fresh DB; permissions matrix for inbox endpoints

Two bootability gaps caught by running the live stack:

1. cyclone.auth.bootstrap.run() called SessionLocal() before db.init_db()
   had run on a fresh DB, so 'python -m cyclone serve' / 'users create'
   / '--help' all crashed with 'db.init_db() has not been called'.
   Add init_db() inside bootstrap (idempotent — no-op once the schema
   is current) so first-boot works without manual prep.

2. PERMISSIONS matrix didn't register the inbox endpoints that were
   added in SP10 (export.csv) and SP14 (candidates/dismiss,
   rejected/resubmit, payer-rejected/acknowledge). The matrix's
   longest-prefix match meant /api/inbox/candidates/dismiss matched
   the '/api/inbox' prefix but only because that single entry
   existed; adding the dedicated write-prefix entries makes the
   intent explicit and keeps viewer role out of every inbox write
   even if the broader /api/inbox prefix is later broadened.

Verified live:
- admin can login, GET /api/inbox/lanes (200), GET
  /api/inbox/export.csv (200), POST /api/inbox/candidates/dismiss
  (200).
- viewer can login, GET /api/inbox/lanes (200), GET
  /api/inbox/export.csv (200), but POST /api/inbox/candidates/dismiss
  and POST /api/inbox/rejected/resubmit both return 403.

backend/src/cyclone/auth/bootstrap.py

@@ -45,6 +45,16 @@ def run() -> None:
     username = os.environ.get("CYCLONE_ADMIN_USERNAME")
     password = os.environ.get("CYCLONE_ADMIN_PASSWORD")
 
+    # First-boot fix: ``python -m cyclone`` calls bootstrap before any
+    # subcommand or the FastAPI lifespan handler runs, so on a brand-new
+    # DB ``SessionLocal()`` raises "init_db() has not been called".
+    # Initialize here so ``serve``, ``users create``, and friends can
+    # all reach the DB without the operator having to know about
+    # migrations. Idempotent — no-op when the schema is already current.
+    from cyclone import db as _db
+
+    _db.init_db()
+
     with SessionLocal()() as db:
         existing = db.execute(select(User)).scalars().first()
         if existing is not None:

backend/src/cyclone/auth/permissions.py

@@ -41,6 +41,7 @@ PERMISSIONS: dict[tuple[str, str], set[Role]] = {
     ("GET", "/api/dashboard/summary"): ALL_ROLES,
     ("GET", "/api/activity"): ALL_ROLES,
     ("GET", "/api/inbox/lanes"): ALL_ROLES,
+    ("GET", "/api/inbox/export.csv"): ALL_ROLES,
     ("GET", "/api/reconcile"): ALL_ROLES,
     ("GET", "/api/audit-log"): ADMIN_ONLY,
 
@@ -48,6 +49,9 @@ PERMISSIONS: dict[tuple[str, str], set[Role]] = {
     ("POST", "/api/parse-837"): WRITE_ROLES,
     ("POST", "/api/parse-835"): WRITE_ROLES,
     ("POST", "/api/inbox"): WRITE_ROLES,
+    ("POST", "/api/inbox/candidates"): WRITE_ROLES,
+    ("POST", "/api/inbox/rejected"): WRITE_ROLES,
+    ("POST", "/api/inbox/payer-rejected"): WRITE_ROLES,
     ("POST", "/api/reconcile"): WRITE_ROLES,
     ("POST", "/api/resubmit"): WRITE_ROLES,
     ("POST", "/api/acks"): WRITE_ROLES,