fix: remove ANTHROPIC_REASONING_MODEL to decouple thinking from model selection (#2081)

ANTHROPIC_REASONING_MODEL was a non-official env var that forced all
requests with thinking params to use a single "reasoning model",
overriding the user's /model selection. Since new Claude Code versions
send adaptive thinking by default, this caused /model to silently fail.

- Remove reasoning_model field and has_thinking_enabled() from model_mapper
- Simplify map_model() to pure type-based matching (haiku/sonnet/opus)
- Remove reasoning model UI field from provider form
- Retain ANTHROPIC_REASONING_MODEL in ENV_EXCLUDES and override-key
  cleanup lists so legacy configs don't leak into common config

src/components/providers/forms/hooks/useModelState.ts

@@ -14,11 +14,6 @@ function parseModelsFromConfig(settingsConfig: string) {
     const env = cfg?.env || {};
     const model =
       typeof env.ANTHROPIC_MODEL === "string" ? env.ANTHROPIC_MODEL : "";
-    const explicitReasoning =
-      typeof env.ANTHROPIC_REASONING_MODEL === "string"
-        ? env.ANTHROPIC_REASONING_MODEL
-        : "";
-    const reasoning = explicitReasoning || model;
     const small =
       typeof env.ANTHROPIC_SMALL_FAST_MODEL === "string"
         ? env.ANTHROPIC_SMALL_FAST_MODEL
@@ -36,15 +31,15 @@ function parseModelsFromConfig(settingsConfig: string) {
         ? env.ANTHROPIC_DEFAULT_OPUS_MODEL
         : model || small;
 
-    return { model, reasoning, haiku, sonnet, opus };
+    return { model, haiku, sonnet, opus };
   } catch {
-    return { model: "", reasoning: "", haiku: "", sonnet: "", opus: "" };
+    return { model: "", haiku: "", sonnet: "", opus: "" };
   }
 }
 
 /**
  * 管理模型选择状态
- * 支持 ANTHROPIC_MODEL, ANTHROPIC_REASONING_MODEL 和各类型默认模型
+ * 支持 ANTHROPIC_MODEL 和各类型默认模型
  */
 export function useModelState({
   settingsConfig,
@@ -54,9 +49,6 @@ export function useModelState({
   const [claudeModel, setClaudeModel] = useState(
     () => parseModelsFromConfig(settingsConfig).model,
   );
-  const [reasoningModel, setReasoningModel] = useState(
-    () => parseModelsFromConfig(settingsConfig).reasoning,
-  );
   const [defaultHaikuModel, setDefaultHaikuModel] = useState(
     () => parseModelsFromConfig(settingsConfig).haiku,
   );
@@ -93,11 +85,6 @@ export function useModelState({
       const env = cfg?.env || {};
       const model =
         typeof env.ANTHROPIC_MODEL === "string" ? env.ANTHROPIC_MODEL : "";
-      const explicitReasoning =
-        typeof env.ANTHROPIC_REASONING_MODEL === "string"
-          ? env.ANTHROPIC_REASONING_MODEL
-          : "";
-      const reasoning = explicitReasoning || model;
       const small =
         typeof env.ANTHROPIC_SMALL_FAST_MODEL === "string"
           ? env.ANTHROPIC_SMALL_FAST_MODEL
@@ -116,7 +103,6 @@ export function useModelState({
           : model || small;
 
       setClaudeModel(model || "");
-      setReasoningModel(reasoning || "");
       setDefaultHaikuModel(haiku || "");
       setDefaultSonnetModel(sonnet || "");
       setDefaultOpusModel(opus || "");
@@ -129,7 +115,6 @@ export function useModelState({
     (
       field:
         | "ANTHROPIC_MODEL"
-        | "ANTHROPIC_REASONING_MODEL"
         | "ANTHROPIC_DEFAULT_HAIKU_MODEL"
         | "ANTHROPIC_DEFAULT_SONNET_MODEL"
         | "ANTHROPIC_DEFAULT_OPUS_MODEL",
@@ -138,7 +123,6 @@ export function useModelState({
       isUserEditingRef.current = true;
 
       if (field === "ANTHROPIC_MODEL") setClaudeModel(value);
-      if (field === "ANTHROPIC_REASONING_MODEL") setReasoningModel(value);
       if (field === "ANTHROPIC_DEFAULT_HAIKU_MODEL")
         setDefaultHaikuModel(value);
       if (field === "ANTHROPIC_DEFAULT_SONNET_MODEL")
@@ -173,8 +157,6 @@ export function useModelState({
   return {
     claudeModel,
     setClaudeModel,
-    reasoningModel,
-    setReasoningModel,
     defaultHaikuModel,
     setDefaultHaikuModel,
     defaultSonnetModel,