feat(qqbot): add chunked upload with structured error types

The v2 'single POST /v2/{users|groups}/{id}/files' upload path is capped
at ~10 MB inline (base64 'file_data' or 'url'). For larger files the QQ
platform provides a three-step flow:

  1. POST /upload_prepare           → upload_id + pre-signed COS part URLs
  2. PUT each part to its COS URL → POST /upload_part_finish
  3. POST /files with {upload_id}   → file_info token

This commit adds a new gateway/platforms/qqbot/chunked_upload.py module
that implements the flow, wires it into QQAdapter._send_media for local
files (URL uploads keep the existing inline path), and introduces
structured exceptions so the caller can surface actionable error text:

- UploadDailyLimitExceededError  (biz_code 40093002, non-retryable)
- UploadFileTooLargeError        (file exceeds the platform limit)

Both carry file_name / file_size_human / limit_human so the model can
compose user-friendly replies instead of seeing opaque HTTP codes.

The part_finish 40093001 retryable-error loop respects the server-
provided retry_timeout (capped at 10 minutes locally) with a 1 s
polling interval. COS PUTs retry transient failures up to 2 times
with exponential backoff. complete_upload retries up to 2 times.

Covers files up to the platform's ~100 MB per-file limit; before this
the adapter silently rejected anything over ~10 MB.

19 new unit tests under TestChunkedUpload* cover the happy path,
prepare-response parsing, helper functions, part retries, COS PUT
retries, group vs c2c routing, and the structured-error mapping.

Co-authored-by: WideLee <limkuan24@gmail.com>

gateway/platforms/qqbot/__init__.py

@@ -34,6 +34,13 @@ from .crypto import decrypt_secret, generate_bind_key  # noqa: F401
 # -- Utils -----------------------------------------------------------------
 from .utils import build_user_agent, get_api_headers, coerce_list  # noqa: F401
 
+# -- Chunked upload --------------------------------------------------------
+from .chunked_upload import (  # noqa: F401
+    ChunkedUploader,
+    UploadDailyLimitExceededError,
+    UploadFileTooLargeError,
+)
+
 __all__ = [
     # adapter
     "QQAdapter",
@@ -52,4 +59,8 @@ __all__ = [
     "build_user_agent",
     "get_api_headers",
     "coerce_list",
+    # chunked upload
+    "ChunkedUploader",
+    "UploadDailyLimitExceededError",
+    "UploadFileTooLargeError",
 ]