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/workers/worker.py

@@ -1,6 +1,8 @@
-"""arq worker entrypoint (SPEC §2 ``workers/worker.py``).
+"""Worker job functions and the sync-worker lifecycle (refactor §1, §6).
 
-Run with: ``arq workers.worker.WorkerSettings`` (from ``backend/``).
+The process is launched via ``workers.run`` (``WORKER_ROLE`` decides which arq
+workers run). This module only defines the job callables and the two queue
+function-sets; the runner wires them onto the ``interactive`` / ``bulk`` queues.
 """
 
 from __future__ import annotations
@@ -9,10 +11,8 @@ import logging
 import uuid
 from typing import Any
 
-from app.config import get_settings
 from app.outbox.draft_sync import push_draft_to_imap_job, remove_imap_draft_job
 from app.outbox.jobs import send_job
-from app.queue import redis_settings as arq_redis_settings
 from app.sync.actions import (
     delete_thread_job,
     move_job,
@@ -32,41 +32,33 @@ async def sync_bootstrap_account(ctx: dict[str, Any], account_id: str) -> int:
     return count
 
 
-async def on_startup(ctx: dict[str, Any]) -> None:
-    logging.basicConfig(level=get_settings().log_level)
+# Fast, interactive user actions (§6): short timeout, high concurrency.
+INTERACTIVE_FUNCTIONS = [
+    push_flags_job,
+    move_job,
+    move_thread_to_folder_job,
+    delete_thread_job,
+    send_job,
+    push_draft_to_imap_job,
+    remove_imap_draft_job,
+    refresh_account_job,
+]
+
+# Bulk work (§6): long timeout, low concurrency, isolated from interactive jobs.
+BULK_FUNCTIONS = [sync_bootstrap_account]
+
+
+async def sync_on_startup(ctx: dict[str, Any]) -> None:
+    """Sync-worker startup: launch the account-sync supervisor."""
     from app.sync.supervisor import start_supervisor
 
     await start_supervisor(ctx)
-    logger.info("webmail worker started")
+    logger.info("sync worker: supervisor started")
 
 
-async def on_shutdown(ctx: dict[str, Any]) -> None:
-    from app.db import dispose_engine
-    from app.redis_client import close_redis
+async def sync_on_shutdown(ctx: dict[str, Any]) -> None:
+    """Sync-worker shutdown: stop the supervisor (process cleanup is in the runner)."""
     from app.sync.supervisor import stop_supervisor
 
     await stop_supervisor(ctx)
-    await dispose_engine()
-    await close_redis()
-    logger.info("webmail worker stopped")
-
-
-class WorkerSettings:
-    """arq worker configuration."""
-
-    functions = [
-        sync_bootstrap_account,
-        push_flags_job,
-        move_job,
-        move_thread_to_folder_job,
-        delete_thread_job,
-        send_job,
-        push_draft_to_imap_job,
-        remove_imap_draft_job,
-        refresh_account_job,
-    ]
-    on_startup = on_startup
-    on_shutdown = on_shutdown
-    max_jobs = 10  # global worker cap (SPEC §6.3)
-    job_timeout = 3600  # backfill of a large account can be long
-    redis_settings = arq_redis_settings()
+    logger.info("sync worker: supervisor stopped")