feat: update gitignore for attachment system

- Add .vscode/ to ignore IDE-specific files
- Add server to ignore build artifacts
- Add attachments/ to ignore uploaded attachment files
- Maintain clean repository without development artifacts

🤖 Generated with [Claude Code](https://claude.ai/code)

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

.gitignore

@@ -97,3 +97,6 @@ config.json
 *.csr
 *.sublime-project
 *.sublime-workspace
+.vscode/
+server
+attachments/