feat(claude): add model alias mapping and improve key normalization

- Introduced model alias mapping for Claude configurations, enabling upstream and client-facing model name associations.
- Added `computeClaudeModelsHash` to generate a consistent hash for model aliases.
- Implemented `normalizeClaudeKey` function to standardize input API key configuration, including models.
- Enhanced executor to resolve model aliases to upstream names dynamically.
- Updated documentation and configuration examples to reflect new model alias support.

internal/watcher/watcher.go

@@ -423,6 +423,19 @@ func computeOpenAICompatModelsHash(models []config.OpenAICompatibilityModel) str
 	return hex.EncodeToString(sum[:])
 }
 
+// computeClaudeModelsHash returns a stable hash for Claude model aliases.
+func computeClaudeModelsHash(models []config.ClaudeModel) string {
+	if len(models) == 0 {
+		return ""
+	}
+	data, err := json.Marshal(models)
+	if err != nil || len(data) == 0 {
+		return ""
+	}
+	sum := sha256.Sum256(data)
+	return hex.EncodeToString(sum[:])
+}
+
 // SetClients sets the file-based clients.
 // SetClients removed
 // SetAPIKeyClients removed
@@ -760,13 +773,17 @@ func (w *Watcher) SnapshotCoreAuths() []*coreauth.Auth {
 			if key == "" {
 				continue
 			}
-			id, token := idGen.next("claude:apikey", key, ck.BaseURL)
+			base := strings.TrimSpace(ck.BaseURL)
+			id, token := idGen.next("claude:apikey", key, base)
 			attrs := map[string]string{
 				"source":  fmt.Sprintf("config:claude[%s]", token),
 				"api_key": key,
 			}
-			if ck.BaseURL != "" {
-				attrs["base_url"] = ck.BaseURL
+			if base != "" {
+				attrs["base_url"] = base
+			}
+			if hash := computeClaudeModelsHash(ck.Models); hash != "" {
+				attrs["models_hash"] = hash
 			}
 			proxyURL := strings.TrimSpace(ck.ProxyURL)
 			a := &coreauth.Auth{