Enhance chat handling and introduce Caveman feature

- Refactored handleChatCore to include Caveman functionality, allowing for terse-style system prompts to reduce output token usage.
- Updated APIPageClient to manage Caveman settings, including enabling/disabling and selecting compression levels.
- Adjusted AntigravityExecutor to consolidate function declarations for compatibility with Gemini.
- Removed unnecessary console logs during translator initialization across multiple routes.

src/lib/localDb.js

@@ -37,6 +37,8 @@ const DEFAULT_SETTINGS = {
   outboundNoProxy: "",
   mitmRouterBaseUrl: DEFAULT_MITM_ROUTER_BASE,
   rtkEnabled: true,
+  cavemanEnabled: false,
+  cavemanLevel: "full",
 };
 
 function cloneDefaultData() {