feat(provider): add kimi_coding provider for Kimi Coding Plan

Add a dedicated provider entry for the Kimi Coding Plan endpoint
(api.kimi.com/coding) using the Anthropic Messages API transport.

- Register kimi_coding with backend=anthropic
- Use KIMI_CODING_API_KEY env key to avoid clashing with MOONSHOT_API_KEY
- Default api_base set to https://api.kimi.com/coding/v1 so that
  AnthropicProvider._normalize_base_url() + the SDK produce the correct
  /coding/v1/messages request path
- Keywords include kimi-coding, kimi_coding and kimi-for-coding

Closes HKUDS/nanobot#4463

nanobot/config/schema.py

@@ -217,6 +217,7 @@ class ProvidersConfig(Base):
     ovms: ProviderConfig = Field(default_factory=ProviderConfig)  # OpenVINO Model Server (OVMS)
     gemini: ProviderConfig = Field(default_factory=ProviderConfig)
     moonshot: ProviderConfig = Field(default_factory=ProviderConfig)
+    kimi_coding: ProviderConfig = Field(default_factory=ProviderConfig)  # Kimi Coding Plan (Anthropic Messages API)
     minimax: ProviderConfig = Field(default_factory=ProviderConfig)
     minimax_anthropic: ProviderConfig = Field(default_factory=ProviderConfig)  # MiniMax Anthropic endpoint (thinking)
     mistral: ProviderConfig = Field(default_factory=ProviderConfig)

nanobot/providers/registry.py

@@ -417,6 +417,16 @@ PROVIDERS: tuple[ProviderSpec, ...] = (
             ("kimi-k2.7-code-highspeed", {"temperature": 1.0}),
         ),
     ),
+    # Kimi Coding Plan — Anthropic Messages API at api.kimi.com/coding
+    # sk-kimi-* keys; requires User-Agent: claude-code/0.1.0 header.
+    ProviderSpec(
+        name="kimi_coding",
+        keywords=("kimi-coding", "kimi_coding", "kimi-for-coding"),
+        env_key="KIMI_CODING_API_KEY",
+        display_name="Kimi Coding",
+        backend="anthropic",
+        default_api_base="https://api.kimi.com/coding/v1",
+    ),
     # MiniMax: OpenAI-compatible API
     ProviderSpec(
         name="minimax",