fix(worker): use CJS-compatible rrule import for Node ESM runtime

The rrule v2.8.1 package's main field points to a CJS bundle. When the worker
runs under Node 22 with "type": "module", Node resolves to the CJS main which
only has a default export. The previous 'import { RRule } from rrule' worked
during typecheck (TypeScript uses the .d.ts) but crashed at runtime:

  SyntaxError: The requested module 'rrule' does not provide an export named 'RRule'

Use namespace-default import + destructure to handle both CJS and ESM at runtime
while preserving the static RRule reference. Verified with node --input-type=module
that RRule.fromString works correctly.

This was a deploy blocker: docker compose up kept restarting the worker.

worker/index.ts

@@ -1,7 +1,8 @@
 import { db, jobs, webhooks, webhookDeliveries, scheduledJobs, tasks, habits, habitCompletions } from '@project-e/db';
 import { and, eq, lte, isNull, sql } from 'drizzle-orm';
 import { createHmac } from 'node:crypto';
-import { RRule } from 'rrule';
+import rrule from 'rrule';
+const { RRule } = rrule;
 
 const POLL_INTERVAL_BASE = 5000; // 5 seconds base
 const POLL_INTERVAL_MAX = 60000; // 60 seconds max