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/account-manager/index.js

@@ -14,7 +14,8 @@ import {
     resetAllRateLimits as resetLimits,
     markRateLimited as markLimited,
     markInvalid as markAccountInvalid,
-    getMinWaitTimeMs as getMinWait
+    getMinWaitTimeMs as getMinWait,
+    getRateLimitInfo as getLimitInfo
 } from './rate-limits.js';
 import {
     getTokenForAccount as fetchToken,
@@ -214,6 +215,16 @@ export class AccountManager {
         return getMinWait(this.#accounts, modelId);
     }
 
+    /**
+     * Get rate limit info for a specific account and model
+     * @param {string} email - Email of the account
+     * @param {string} modelId - Model ID to check
+     * @returns {{isRateLimited: boolean, actualResetMs: number|null, waitMs: number}} Rate limit info
+     */
+    getRateLimitInfo(email, modelId) {
+        return getLimitInfo(this.#accounts, email, modelId);
+    }
+
     /**
      * Get OAuth token for an account
      * @param {Object} account - Account object with email and credentials