feat: add video OCR/ASR, DOCX/PDF export, input block and risk config updates

- Video pipeline: video file OCR via VLM plus audio track ASR, integrated
  into job_handlers with progress emit per phase. New media_utils.py for
  audio extraction from video files.
- Document export: richExport.js replaces inline docx builder; DOCX and PDF
  export buttons are now enabled in MilkdownEditor. File size limit raised to
  100 MB.
- Input block: new InputBlockCrepe.vue component with inputBlockPlugin.ts
  and inputBlock.js for custom user-input nodes in the editor.
- Risk config: added Vite dev server ports (5173) to CORS allowlist and
  increased OCR max input from 10 MB to 100 MB.
- TTS/ASR refactor: simplified tts_asr.py model loading and warmup logic.
- Test coverage: updated tests for llm, main endpoints, pro completions and
  web search modules.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/tests/test_pro_completions.py

@@ -35,7 +35,7 @@ def _payload():
         "privacy_mode": True,
         "user_preferences": {
             "language": "zh",
-            "currency": "CNY",
+            "country": "CN",
             "timezone": "Asia/Shanghai",
         },
     }
@@ -43,7 +43,7 @@ def _payload():
 
 def test_pro_queue_full_returns_429(monkeypatch):
     async def fake_queue_job(*args, **kwargs):
-        raise job_system.QueueFullError("pro_completion queue is full")
+        raise job_system.QueueFullError("pro_completion", 8)
 
     monkeypatch.setattr(main, "_queue_job", fake_queue_job)
     with TestClient(main.app) as client:
@@ -79,13 +79,13 @@ def test_pro_prompt_accepts_serialized_preferences():
         instruction="expand",
         preferences={
             "language": "zh",
-            "currency": "CNY",
+            "country": "CN",
             "timezone": "Asia/Shanghai",
         },
     )
 
     assert "Preferred language: zh" in user_prompt
-    assert "Preferred currency: CNY" in user_prompt
+    assert "Preferred country: CN" in user_prompt
     assert "Preferred timezone: Asia/Shanghai" in user_prompt