feat(auth): enhance Antigravity token refresh with robust error handling and retry logic

- Add AntigravityTokenRefreshError custom error class with code, description, and status fields
- Implement parseOAuthErrorPayload() for parsing Google's various OAuth error response formats
- Add retry logic with exponential backoff (3 retries, 1s→2s→4s delay) for transient failures
- Add special handling for invalid_grant error - immediately throws without retry and clears caches
- Add invalidateProjectContextByRefreshToken() for selective cache invalidation
- Update fetch.ts error handling to work with new error class and cache invalidation

🤖 Generated with assistance of OhMyOpenCode (https://github.com/code-yeongyu/oh-my-opencode)

src/hooks/anthropic-auto-compact/parser.ts

@@ -26,6 +26,7 @@ const TOKEN_LIMIT_KEYWORDS = [
   "context length",
   "too many tokens",
   "non-empty content",
+  "invalid_request_error",
 ]
 
 const MESSAGE_INDEX_PATTERN = /messages\.(\d+)/
@@ -114,9 +115,10 @@ export function parseAnthropicTokenLimitError(err: unknown): ParsedTokenLimitErr
   if (typeof responseBody === "string") {
     try {
       const jsonPatterns = [
-        /data:\s*(\{[\s\S]*?\})\s*$/m,
-        /(\{"type"\s*:\s*"error"[\s\S]*?\})/,
-        /(\{[\s\S]*?"error"[\s\S]*?\})/,
+        // Greedy match to last } for nested JSON
+        /data:\s*(\{[\s\S]*\})\s*$/m,
+        /(\{"type"\s*:\s*"error"[\s\S]*\})/,
+        /(\{[\s\S]*"error"[\s\S]*\})/,
       ]
 
       for (const pattern of jsonPatterns) {