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/commands/install.py

@@ -38,7 +38,7 @@ def write_native_host_exe(path: Path) -> None:
       encoding="utf-8",
     )
   else:
-    path.write_text(f'#!{sys.executable}\nfrom browser_cli.native.host import main\nmain()\n')
+    path.write_text(f'#!{sys.executable}\nfrom browser_cli.native.host import main\nmain()\n', encoding="utf-8")
     path.chmod(path.stat().st_mode | 0o111)
 
 def _windows_registry_views():
@@ -156,7 +156,7 @@ def _install_manifest(browser: str, host_exe: Path, manifest: dict) -> list:
     try:
       directory.mkdir(parents=True, exist_ok=True)
       manifest_path = directory / f"{NATIVE_HOST_NAME}.json"
-      manifest_path.write_text(json.dumps(manifest, indent=2))
+      manifest_path.write_text(json.dumps(manifest, indent=2), encoding="utf-8")
       installed.append(manifest_path)
     except Exception as e:
       console.print(f"[yellow]Could not write to {directory}: {e}[/yellow]")