fix(server): scope --reload watching to source dirs (#569)

[voidborne-d]

Summary

Closes #569.

When python server_main.py --reload is used during development, uvicorn defaults reload_dirs to the current working directory and StatReload recursively walks the tree for *.py files. Because the agent writes generated code into WareHouse/session_<uuid>/code_workspace/<file>.py, every time a workflow produces code the server restarts mid-run, the in-flight session is cancelled, and the webui is left waiting indefinitely.

Both READMEs already ship a warning telling users to drop --reload, but that removes exactly the feedback loop developers need.

Fix

server_main.py now passes uvicorn:

• an explicit reload_dirs list restricted to the project's Python source folders (check, entity, functions, mcp_example, runtime, schema_registry, server, tools, utils, workflow), so StatReload — which ignores reload_excludes entirely — never walks WareHouse/ or logs/;
• a matching reload_excludes list (WareHouse/*, logs/*, data/*, temp/*, node_modules/*) so watchfiles-backed installs also stop observing output dirs. This set mirrors .gitignore.

Users can override either list via repeatable --reload-dir / --reload-exclude flags.

The reload-kwargs construction is extracted into a pure helper (build_reload_kwargs) so the behaviour is unit-testable without spinning up a server.

Changes

• server_main.py: define RELOAD_SOURCE_DIRS / RELOAD_EXCLUDES, add build_reload_kwargs() + build_parser() helpers, wire new CLI flags, pass the resulting kwargs to uvicorn.run(...).
• tests/test_server_main_reload.py: 9 new tests (defaults exclude WareHouse, include server/runtime; overrides win; repeatable flags; returned lists are copies). Uses an importlib.util spec loader + monkeypatch.setitem(sys.modules, ...) so stubs for runtime.bootstrap / server.app are fully isolated from the rest of the test suite.
• README.md / README-zh.md: replaced the "remove --reload" workaround note with a description of the new default and the override flags.

Verification

$ uv run python -m pytest tests/test_server_main_reload.py tests/test_websocket_send_message_sync.py -v
...
16 passed in 22.07s

• build_parser().print_help() renders the new --reload-dir / --reload-exclude options.
• No change to the non---reload code path.
• CI (Validate YAML Workflows) does not watch these paths, so it should stay green.