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.

tests/test_auth.py

@@ -163,7 +163,7 @@ class TestAuthorizedKeys:
 
     def test_ignores_comment_lines(self, tmp_path):
         path = tmp_path / "authorized_keys"
-        path.write_text("# this is a comment\n")
+        path.write_text("# this is a comment\n", encoding="utf-8")
         assert load_authorized_keys(path) == []
 
     def test_returns_empty_for_missing_file(self, tmp_path):