fix: accurate quota reporting with project ID and improved rate limit handling

- Pass project ID to fetchAvailableModels for accurate per-project quota
- Treat missing remainingFraction with resetTime as 0% (exhausted)
- Fix double-escaped regex in rate-limit-parser.js (\\d -> \d)
- Use ANTIGRAVITY_HEADERS for loadCodeAssist consistency
- Store actual reset time from API instead of capping at default
- Add getRateLimitInfo() for detailed rate limit state
- Handle disabled accounts in rate limit checks

Fixes issue where free tier accounts showed 100% quota but were actually exhausted.

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

src/constants.js

@@ -69,15 +69,16 @@ export const ONBOARD_USER_ENDPOINTS = ANTIGRAVITY_ENDPOINT_FALLBACKS;
 
 // Hybrid headers specifically for loadCodeAssist
 // Uses google-api-nodejs-client User-Agent (required for project discovery on some accounts)
-export const LOAD_CODE_ASSIST_HEADERS = {
-    'User-Agent': 'google-api-nodejs-client/9.15.1',
-    'X-Goog-Api-Client': 'google-cloud-sdk vscode_cloudshelleditor/0.1',
-    'Client-Metadata': JSON.stringify({
-        ideType: 'IDE_UNSPECIFIED',
-        platform: 'PLATFORM_UNSPECIFIED',
-        pluginType: 'GEMINI'
-    })
-};
+// export const LOAD_CODE_ASSIST_HEADERS = {
+//     'User-Agent': 'google-api-nodejs-client/9.15.1',
+//     'X-Goog-Api-Client': 'google-cloud-sdk vscode_cloudshelleditor/0.1',
+//     'Client-Metadata': JSON.stringify({
+//         ideType: 'IDE_UNSPECIFIED',
+//         platform: 'PLATFORM_UNSPECIFIED',
+//         pluginType: 'GEMINI'
+//     })
+// };
+export const LOAD_CODE_ASSIST_HEADERS = ANTIGRAVITY_HEADERS;
 
 // Default project ID if none can be discovered
 export const DEFAULT_PROJECT_ID = 'rising-fact-p41fc';