fix: restore Python 3.10/3.11 support and report MCP version

- Drop backslash from f-string expression in markdown/html.py
- That syntax needs 3.12+ (PEP 701) and broke import on 3.10/3.11
- Add Python matrix 3.10/3.12/3.14/3.15 to the Gitea testing workflow
- Pass project_version() to MCPServer; serverInfo.version was empty
- Cover the reported version with an in-memory MCP client test
- Swap deprecated click.get_text_stream for sys.stdin.isatty()
- Add explicit encoding to native host shim and manifest writes
- Add explicit encoding to the registry lock file open
- Add explicit encoding to every read_text/write_text call in tests
- Bump version to 0.16.10 in pyproject.toml and extension/manifest.json
- Move .python-version to 3.15 and refresh uv.lock

Extension code is unchanged; only the manifest version string moved.

Verified with 778 tests on 3.10 through 3.15, plus a strict run using -X warn_default_encoding with EncodingWarning and DeprecationWarning as errors.

browser_cli/registry.py

@@ -15,7 +15,7 @@ def _file_lock(path: Path) -> Iterator[None]:
     """Best-effort cross-process lock for registry read/modify/write updates."""
     path.parent.mkdir(mode=0o700, parents=True, exist_ok=True)
     lock_path = path.with_suffix(path.suffix + ".lock")
-    with lock_path.open("a+") as lock_file:
+    with lock_path.open("a+", encoding="utf-8") as lock_file:
         if os.name == "nt":
             try:
                 import msvcrt