Add error reporting for GitHub rate limit errors

- Add specific error handling for GitHub API rate limit (403) errors
- Create RateLimitError with proper error name for identification
- Store last sync error and error time in settings for UI display
- Add error status display in autosync settings modal
- Show user-friendly error messages with GitHub token suggestion
- Clear error status on successful sync
- Update both GitHubJsonService and GitHubService with rate limit error handling

This provides better user feedback when GitHub API rate limits are exceeded
and guides users to set up a GitHub token for higher rate limits.

src/server/services/githubJsonService.ts

@@ -50,16 +50,15 @@ export class GitHubJsonService {
     // Add GitHub token authentication if available
     if (env.GITHUB_TOKEN) {
       headers.Authorization = `token ${env.GITHUB_TOKEN}`;
-      console.log('Using GitHub token for API authentication');
-    } else {
-      console.log('No GitHub token found, using unauthenticated requests (lower rate limits)');
     }
     
     const response = await fetch(`${this.baseUrl!}${endpoint}`, { headers });
 
     if (!response.ok) {
       if (response.status === 403) {
-        throw new Error(`GitHub API rate limit exceeded. Consider setting GITHUB_TOKEN for higher limits. Status: ${response.status} ${response.statusText}`);
+        const error = new Error(`GitHub API rate limit exceeded. Consider setting GITHUB_TOKEN for higher limits. Status: ${response.status} ${response.statusText}`);
+        error.name = 'RateLimitError';
+        throw error;
       }
       throw new Error(`GitHub API error: ${response.status} ${response.statusText}`);
     }
@@ -83,7 +82,9 @@ export class GitHubJsonService {
     const response = await fetch(rawUrl, { headers });
     if (!response.ok) {
       if (response.status === 403) {
-        throw new Error(`GitHub rate limit exceeded while downloading ${filePath}. Consider setting GITHUB_TOKEN for higher limits. Status: ${response.status} ${response.statusText}`);
+        const error = new Error(`GitHub rate limit exceeded while downloading ${filePath}. Consider setting GITHUB_TOKEN for higher limits. Status: ${response.status} ${response.statusText}`);
+        error.name = 'RateLimitError';
+        throw error;
       }
       throw new Error(`Failed to download ${filePath}: ${response.status} ${response.statusText}`);
     }