sync-v2 step 1: worker roles + interactive/bulk queue split

- config: WORKER_ROLE (sync|jobs|all), INTERACTIVE_CONCURRENCY, BULK_CONCURRENCY.
- queue: named queues (interactive/bulk) + enqueue_job() router; sync_bootstrap
  goes to bulk, all other jobs to interactive.
- workers.run: single entrypoint; role=jobs runs both arq consumers (per-queue
  timeout/concurrency), role=sync runs the supervisor, all=both (dev default).
- docker-compose: worker-sync + worker-jobs services (shared image, nofile
  ulimit); backend/Dockerfile; Makefile worker/worker-sync/worker-jobs targets.
- tests repointed to app.queue.get_arq_pool; supervisor behavior unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/api/accounts.py

@@ -30,7 +30,7 @@ from app.api.schemas import AccountOut
 from app.db import get_session
 from app.identity.deps import CurrentUser, require_csrf
 from app.models import Account
-from app.queue import get_arq_pool
+from app.queue import enqueue_job
 from app.redis_client import get_redis
 from app.security.crypto import encrypt_secret
 
@@ -91,9 +91,8 @@ async def list_accounts(user: CurrentUser, db: DbSession) -> list[AccountOut]:
 async def sync_all_accounts(user: CurrentUser, db: DbSession) -> dict[str, str]:
     """Poll every folder of each of the user's accounts (manual Refresh)."""
     account_ids = list(await db.scalars(select(Account.id).where(Account.user_id == user.id)))
-    pool = await get_arq_pool()
     for account_id in account_ids:
-        await pool.enqueue_job("refresh_account_job", str(account_id))
+        await enqueue_job("refresh_account_job", str(account_id))
     return {"status": "queued"}
 
 
@@ -145,8 +144,7 @@ async def create_new_account(
         raise_api_error(409, "account_exists", "an account for this email already exists")
     await db.commit()
 
-    pool = await get_arq_pool()
-    await pool.enqueue_job("sync_bootstrap_account", str(account.id))
+    await enqueue_job("sync_bootstrap_account", str(account.id))
 
     return _detail(account)
 
@@ -227,8 +225,7 @@ async def update_account(
     await db.commit()
 
     if conn_change:
-        pool = await get_arq_pool()
-        await pool.enqueue_job("sync_bootstrap_account", str(account.id))
+        await enqueue_job("sync_bootstrap_account", str(account.id))
 
     return _detail(account)