perf: Fix all 7 code analysis issues

HIGH (Performance):
- Replace 8 sync file operations with aiofiles in async context (storage, mail,
  report_generator, dms_bridge, ai_assistant)
- Frontend bundle splitting: manualChunks for react-vendor, ui-components, tanstack,
  markdown, icons, utils, i18n (ui chunk 936K → ~19K)

MEDIUM (Architecture):
- Worker circular deps: Replace direct plugin imports with job_registry.py pattern
  (register_job/get_all_jobs, importlib-based lazy loading)
- App-wide ErrorBoundary: New ErrorBoundary.tsx component, wrapped in AppShell
  and all standalone routes

LOW (Code Quality):
- N+1 query fix: selectinload(Contact.contact_persons) in list_contacts()
- O(n²) dedup fix: SQL GROUP BY for email/phone duplicates, Dict-based name grouping
- Response format standardization: 7 routes converted from plain arrays to
  {items: [...], total: N} format

app/plugins/builtins/unified_search/jobs.py

@@ -249,3 +249,14 @@ async def embedding_batch(ctx: dict[str, Any]) -> None:
                     pass
 
     logger.info("Embedding batch job complete")
+
+
+# Register all job functions with the job registry
+from app.core.job_registry import register_job
+
+register_job("index_mails", index_mails)
+register_job("index_file", index_file)
+register_job("index_contact", index_contact)
+register_job("index_event", index_event)
+register_job("reindex", reindex)
+register_job("embedding_batch", embedding_batch)