Merge master into the OpenCode Go branch

Master grew Google AI Studio and Antigravity as providers, a doctor that
names each provider's own key, and settings that fetch every hosted
model list as the window opens. OpenCode Go is folded into each: its
name joins SERVICES and the doctor's key table, its key row sits beside
Google's, its Fetch button follows the per-provider pattern Google's
uses, and _load_hosted_models fetches its catalog at open when a key is
on file, filling the cleanup and agent boxes alike.

tests/test_config.py

@@ -187,6 +187,8 @@ class Keys(DikteTest):
     def test_every_provider_falls_back_to_the_variable_of_its_own_name(self):
         with mock.patch.dict(os.environ, {"GROQ_API_KEY": "gsk-env"}):
             self.assertEqual(cfg.Config().groq_key(), "gsk-env")
+        with mock.patch.dict(os.environ, {"GEMINI_API_KEY": "AIza-env"}):
+            self.assertEqual(cfg.Config().gemini_key(), "AIza-env")
         with mock.patch.dict(os.environ, {"OPENCODE_API_KEY": "opencode-env"}):
             self.assertEqual(cfg.Config().opencode_key(), "opencode-env")
 
@@ -576,8 +578,14 @@ class Defaults(unittest.TestCase):
     def test_the_keys_ship_empty(self):
         self.assertEqual(cfg.DEFAULTS["openai_api_key"], "")
         self.assertEqual(cfg.DEFAULTS["openrouter_api_key"], "")
+        self.assertEqual(cfg.DEFAULTS["gemini_api_key"], "")
         self.assertEqual(cfg.DEFAULTS["opencode_api_key"], "")
 
+    def test_google_ai_studio_is_a_cleanup_provider_and_not_a_transcriber(self):
+        """Its compatible endpoint has no /audio/transcriptions behind it."""
+        self.assertNotIn("gemini", cfg.TRANSCRIBERS)
+        self.assertIn("gemini", cleanup.PROVIDERS)
+
     def test_opencode_ships_on_its_own_endpoint(self):
         self.assertEqual(cfg.DEFAULTS["opencode_base_url"],
                          "https://opencode.ai/zen/go/v1")