fix(server): stop bare excepts from swallowing cancellation and shutdown

[harshadkhetpal]

Summary

Replaces the 18 bare except: clauses in lightllm/server/ (ruff E722). A bare except catches BaseException, which in an async serving stack silently swallows asyncio.CancelledError, KeyboardInterrupt, and SystemExit — 8 of these sites are in httpserver_for_pd_master/manager.py, on the PD-master request lifecycle (abort fallbacks, status updates, request-table cleanup), where an eaten cancellation can leak or hang a request instead of unwinding it.

Chosen replacements:

• except Exception: for the 15 intentional catch-and-continue sites — identical behavior for all ordinary errors, but cancellation/shutdown now propagates.
• except (AttributeError, TypeError): for the two chat_template capability probes in build_prompt.py (the only failures attribute probing produces).
• except OSError: for the temp-file unlink cleanup in embed_cache/afs_utils.py.

Testing

python -m py_compile passes on all nine files; ruff check --select E722 on lightllm/server/ goes from 18 errors to clean. No functional change for ordinary exceptions — only BaseException-family propagation is restored.

🤖 Generated with Claude Code