M1/F2+F4: platform registry, Moonshot API-key channel, dynamic model sync

F2 — fixed three-platform registry in kigi-models: kimi-code
(subscription, OAuth bearer, base kigi_env::coding_api_base_url()),
moonshot-cn (https://api.moonshot.cn/v1), moonshot-ai
(https://api.moonshot.ai/v1) with kimi-k model-prefix filtering.
Moonshot API keys via KIGI_MOONSHOT_CN_API_KEY / KIGI_MOONSHOT_AI_API_KEY
(+ KIGI_MOONSHOT_API_KEY shared fallback) or ~/.kigi/config.toml;
values redacted from logs/display.

F4 — model catalog now syncs from GET {base}/models (Bearer auth,
wire shape per official kimi-cli: id/context_length/supports_reasoning/
supports_image_in/supports_video_in/display_name) with the official
capability-derivation rules (thinking / always_thinking-in-name /
kimi-k2 implicit set). Managed keys {platform_id}/{model_id}; default
model = first list entry; default thinking iff capabilities contain
thinking/always_thinking. Sync failure → last cache; no cache →
built-in fallback table seeded from ids sourced in official kimi-cli
(kimi-for-coding, kimi-k2-turbo-preview, kimi-k2-thinking-turbo).
401 during sync forces one token refresh and retries.

Model resolution priority preserved: CLI > env > config > server >
fallback. Grok model artifacts (grok-4*/grok-build catalog, tier
gating remnants) removed from non-test code.

All first-party endpoints re-verified live: device_authorization mints
real codes; /models on all three platforms answers with real API auth
errors when unauthenticated.

Gates: check/clippy --all-targets 0/0, fmt clean, deny ok,
kigi-shell lib 5136 green, kigi-tui lib 6819 green, kigi-models 8.

crates/codegen/kigi-models/default_models.json

@@ -1,18 +1,46 @@
 {
-  "default": "grok-build",
-  "web_search": "grok-4.20-multi-agent",
-  "image_description": "grok-build",
-  "session_summary": "grok-build",
+  "default": "kimi-for-coding",
   "models": [
     {
-      "model": "grok-build",
-      "name": "Grok Build",
-      "description": "Best for advanced coding tasks",
-      "context_window": 500000,
-      "temperature": 0.7,
-      "top_p": 0.95,
-      "api_backend": "responses",
+      "id": "kimi-code/kimi-for-coding",
+      "model": "kimi-for-coding",
+      "name": "Kimi for Coding",
+      "description": "Kimi Code subscription coding model (offline fallback entry)",
+      "context_window": 262144,
+      "capabilities": ["thinking", "image_in", "video_in"],
       "supported_in_api": false
+    },
+    {
+      "id": "moonshot-cn/kimi-k2-turbo-preview",
+      "model": "kimi-k2-turbo-preview",
+      "name": "Kimi K2 Turbo (moonshot.cn)",
+      "description": "Moonshot open platform model (offline fallback entry)",
+      "context_window": 262144,
+      "capabilities": ["thinking", "image_in", "video_in"]
+    },
+    {
+      "id": "moonshot-cn/kimi-k2-thinking-turbo",
+      "model": "kimi-k2-thinking-turbo",
+      "name": "Kimi K2 Thinking Turbo (moonshot.cn)",
+      "description": "Moonshot open platform model (offline fallback entry)",
+      "context_window": 262144,
+      "capabilities": ["thinking", "always_thinking", "image_in", "video_in"]
+    },
+    {
+      "id": "moonshot-ai/kimi-k2-turbo-preview",
+      "model": "kimi-k2-turbo-preview",
+      "name": "Kimi K2 Turbo (moonshot.ai)",
+      "description": "Moonshot open platform model (offline fallback entry)",
+      "context_window": 262144,
+      "capabilities": ["thinking", "image_in", "video_in"]
+    },
+    {
+      "id": "moonshot-ai/kimi-k2-thinking-turbo",
+      "model": "kimi-k2-thinking-turbo",
+      "name": "Kimi K2 Thinking Turbo (moonshot.ai)",
+      "description": "Moonshot open platform model (offline fallback entry)",
+      "context_window": 262144,
+      "capabilities": ["thinking", "always_thinking", "image_in", "video_in"]
     }
   ]
 }