fix: hide dot directories in code browser

[Ziinc]

Motivation

• Prevent implementation metadata directories like .jj, .git, and other dot-prefixed directories from appearing in the Code tab directory tree while keeping useful dot-files visible.

Description

• Replace previous .git/.treq whitelist with a filter that excludes all dot-prefixed directories in FileBrowser.
• Add an integration test asserting dot-directories are hidden and dot-files remain visible.
• Update imports/formatting and commit the change.

Testing

• Ran project formatting and TypeScript checks with npx biome format and tsc --noEmit, which passed.
• Ran unit tests via npm run test:unit, which completed successfully.
• Attempted integration run but NAPI build failed due to missing system library (glib-2.0) in the environment, preventing the integration test run.
  [Codex Task](

[github-actions]

🚀 Web preview: https://preview-388.treq-9zy.pages.dev
📊 Lighthouse report: https://github.com/treq-dev/treq/actions/runs/33323138955/artifacts/9735634141