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_serve.py

@@ -74,7 +74,7 @@ class TestChallenge:
     monkeypatch.setattr("browser_cli.auth.pq_kex_server_keypair", lambda: ("fake-private", b"fake-public"))
     path = tmp_path / "authorized_keys"
     _, pub = generate_keypair()
-    path.write_text(pub + "\n")
+    path.write_text(pub + "\n", encoding="utf-8")
 
     client, server = _pair()
     t = _spawn(server, path)
@@ -106,7 +106,7 @@ class TestRejection:
   def test_missing_pubkey_sig_rejected(self, tmp_path):
     path = tmp_path / "authorized_keys"
     _, pub = generate_keypair()
-    path.write_text(pub + "\n")
+    path.write_text(pub + "\n", encoding="utf-8")
     client, t, _ = self._connect(path)
     msg = {"id": "x", "command": "tabs.list", "args": {}, "user_agent": FAKE_UA}
     _send_framed(client, json.dumps(msg).encode())
@@ -119,7 +119,7 @@ class TestRejection:
   def test_untrusted_pubkey_rejected(self, tmp_path):
     path = tmp_path / "authorized_keys"
     _, trusted_pub = generate_keypair()
-    path.write_text(trusted_pub + "\n")
+    path.write_text(trusted_pub + "\n", encoding="utf-8")
 
     pem, untrusted_pub = generate_keypair()
     key_path = tmp_path / "other.pem"
@@ -140,7 +140,7 @@ class TestRejection:
   def test_bad_signature_rejected(self, tmp_path):
     path = tmp_path / "authorized_keys"
     _, pub = generate_keypair()
-    path.write_text(pub + "\n")
+    path.write_text(pub + "\n", encoding="utf-8")
     client, t, _ = self._connect(path)
     msg = {"id": "x", "command": "tabs.list", "args": {}, "user_agent": FAKE_UA, "pubkey": pub, "sig": "00" * 64}
     _send_framed(client, json.dumps(msg).encode())
@@ -154,7 +154,7 @@ class TestRejection:
     monkeypatch.setattr("browser_cli.auth.pq_kex_server_keypair", lambda: ("fake-private", b"fake-public"))
     path = tmp_path / "authorized_keys"
     pem, pub = generate_keypair()
-    path.write_text(pub + "\n")
+    path.write_text(pub + "\n", encoding="utf-8")
     priv_path = tmp_path / "client.pem"
     priv_path.write_bytes(pem)
     priv = load_private_key(priv_path)
@@ -200,7 +200,7 @@ class TestAuthSuccess:
     """Correct signature → error must be 'browser not connected', not 'unauthorized'."""
     path = tmp_path / "authorized_keys"
     pem, pub = generate_keypair()
-    path.write_text(pub + "\n")
+    path.write_text(pub + "\n", encoding="utf-8")
     key_path = tmp_path / "client.key.pem"
     key_path.write_bytes(pem)
     priv = load_private_key(key_path)
@@ -236,7 +236,7 @@ class TestAuthSuccess:
 
     path = tmp_path / "authorized_keys"
     pem, pub = generate_keypair()
-    path.write_text(pub + "\n")
+    path.write_text(pub + "\n", encoding="utf-8")
     key_path = tmp_path / "client.key.pem"
     key_path.write_bytes(pem)
     priv = load_private_key(key_path)
@@ -276,7 +276,7 @@ class TestAuthSuccess:
 
     path = tmp_path / "authorized_keys"
     pem, pub = generate_keypair()
-    path.write_text(pub + "\n")
+    path.write_text(pub + "\n", encoding="utf-8")
     key_path = tmp_path / "client.key.pem"
     key_path.write_bytes(pem)
     priv = load_private_key(key_path)
@@ -411,7 +411,7 @@ class TestPerKeyPolicy:
     monkeypatch.setattr("browser_cli.client.targets.resolve_socket", _mock_no_browser)
     path = tmp_path / "authorized_keys"
     pem, pub = generate_keypair()
-    path.write_text(pub + "\n")
+    path.write_text(pub + "\n", encoding="utf-8")
     key_path = tmp_path / "client.key.pem"
     key_path.write_bytes(pem)
     priv = load_private_key(key_path)
@@ -441,7 +441,7 @@ class TestPerKeyPolicy:
 
     path = tmp_path / "authorized_keys"
     pem, pub = generate_keypair()
-    path.write_text(pub + " mykey\n")
+    path.write_text(pub + " mykey\n", encoding="utf-8")
     key_path = tmp_path / "client.key.pem"
     key_path.write_bytes(pem)
     priv = load_private_key(key_path)