refactor(claude): migrate api_format from settings_config to meta

Move api_format storage from settings_config to ProviderMeta to prevent
polluting ~/.claude/settings.json when switching providers.

- Add api_format field to ProviderMeta (Rust + TypeScript)
- Update ProviderForm to read/write apiFormat from meta
- Maintain backward compatibility for legacy settings_config.api_format
  and openrouter_compat_mode fields (read-only fallback)
- Strip api_format from settings_config before writing to live config

src-tauri/src/services/proxy.rs

@@ -1654,7 +1654,8 @@ impl ProxyService {
 
     fn write_claude_live(&self, config: &Value) -> Result<(), String> {
         let path = get_claude_settings_path();
-        write_json_file(&path, config).map_err(|e| format!("写入 Claude 配置失败: {e}"))
+        let settings = crate::services::provider::sanitize_claude_settings_for_live(config);
+        write_json_file(&path, &settings).map_err(|e| format!("写入 Claude 配置失败: {e}"))
     }
 
     fn read_codex_live(&self) -> Result<Value, String> {