feat: Change default OpenRouter model to xiaomi/mimo-v2-flash:free

Updated default in 4 locations:
- src/shared/SettingsDefaultsManager.ts
- src/services/worker/OpenRouterAgent.ts
- src/ui/viewer/constants/settings.ts
- src/ui/viewer/components/ContextSettingsModal.tsx

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/ui/viewer/components/ContextSettingsModal.tsx

@@ -513,9 +513,9 @@ export function ContextSettingsModal({
                   >
                     <input
                       type="text"
-                      value={formState.CLAUDE_MEM_OPENROUTER_MODEL || 'anthropic/claude-3.5-sonnet'}
+                      value={formState.CLAUDE_MEM_OPENROUTER_MODEL || 'xiaomi/mimo-v2-flash:free'}
                       onChange={(e) => updateSetting('CLAUDE_MEM_OPENROUTER_MODEL', e.target.value)}
-                      placeholder="e.g., anthropic/claude-3.5-sonnet"
+                      placeholder="e.g., xiaomi/mimo-v2-flash:free"
                     />
                   </FormField>
                   <FormField

src/ui/viewer/constants/settings.ts

@@ -13,7 +13,7 @@ export const DEFAULT_SETTINGS = {
   CLAUDE_MEM_GEMINI_API_KEY: '',
   CLAUDE_MEM_GEMINI_MODEL: 'gemini-2.5-flash-lite',
   CLAUDE_MEM_OPENROUTER_API_KEY: '',
-  CLAUDE_MEM_OPENROUTER_MODEL: 'anthropic/claude-3.5-sonnet',
+  CLAUDE_MEM_OPENROUTER_MODEL: 'xiaomi/mimo-v2-flash:free',
   CLAUDE_MEM_OPENROUTER_SITE_URL: '',
   CLAUDE_MEM_OPENROUTER_APP_NAME: 'claude-mem',
   CLAUDE_MEM_GEMINI_RATE_LIMITING_ENABLED: 'true',