fix: update Gemini model catalog + wire models.dev as live model source

Follow-up for salvaged PR #5494:
- Update model catalog to Gemini 3.x + Gemma 4 (drop deprecated 2.0)
- Add list_agentic_models() to models_dev.py with noise filter
- Wire models.dev into _model_flow_api_key_provider as primary source
  (static curated list serves as offline fallback)
- Add gemini -> google mapping in PROVIDER_TO_MODELS_DEV
- Fix Gemma 4 context lengths to 256K (models.dev values)
- Update auxiliary model to gemini-3-flash-preview
- Expand tests: 3.x catalog, context lengths, models.dev integration

hermes_cli/setup.py

@@ -112,8 +112,9 @@ _DEFAULT_PROVIDER_MODELS = {
         "grok-code-fast-1",
     ],
     "gemini": [
-        "gemini-2.5-pro", "gemini-2.5-flash", "gemini-2.0-flash", "gemini-2.0-flash-lite",
-        "gemma-4-31b-it", "gemma-4-26b-a4b-it", "gemma-4-e4b-it", "gemma-4-e2b-it",
+        "gemini-3.1-pro-preview", "gemini-3-flash-preview", "gemini-3.1-flash-lite-preview",
+        "gemini-2.5-pro", "gemini-2.5-flash", "gemini-2.5-flash-lite",
+        "gemma-4-31b-it", "gemma-4-26b-it",
     ],
     "zai": ["glm-5", "glm-4.7", "glm-4.5", "glm-4.5-flash"],
     "kimi-coding": ["kimi-k2.5", "kimi-k2-thinking", "kimi-k2-turbo-preview"],