refactor: remove dead code and unoptimized structures

src/utils.ts

@@ -85,11 +85,6 @@ export function shouldAutoPushBrain(): boolean {
     const cfg = vscode.workspace.getConfiguration('g1nation');
     return cfg.get<boolean>('autoPushBrain', false);
 }
-
-export function getSecondBrainRepo(): string {
-    return getConfig().secondBrainRepo;
-}
-
 export function getBrainProfiles(): BrainProfile[] {
     return getConfig().brainProfiles;
 }
@@ -107,18 +102,6 @@ export function _isBrainDirExplicitlySet(): boolean {
     return getBrainProfiles().length > 0;
 }
 
-export function isTextAttachment(fileName: string, mimeType: string): boolean {
-    const lower = fileName.toLowerCase();
-    const textExtensions = [
-        '.txt', '.md', '.csv', '.json', '.js', '.ts', '.jsx', '.tsx',
-        '.html', '.css', '.py', '.java', '.rs', '.go', '.yaml', '.yml',
-        '.xml', '.toml', '.sql', '.sh'
-    ];
-    return mimeType.startsWith('text/')
-        || mimeType === 'application/json'
-        || textExtensions.some((ext) => lower.endsWith(ext));
-}
-
 export function findBrainFiles(dir: string): string[] {
     let results: string[] = [];
     if (!fs.existsSync(dir)) return results;