fix(search): find bare filenames throughout the workspace

[jonathanKingston]

find_files currently searches only root-level files for patterns such as package.json and *.ts, so agents miss nested packages and source files.

Match basename-only patterns at every depth while keeping directory-qualified globs such as src/*.ts scoped as before. Regression tests cover both behaviors.

Validation: pnpm run check. The nested-filename regression fails on current main. Search plumbing only; no DOM or layout changes.

[github-actions]

🖥️ PR preview

• Marketing site
• Browser demo
  Interactive, with a mocked backend — jump to a scenario:
• Builds a cupcake site
• Agent-proposed edits open the Changes panel
• Markdown list indentation
• Responsive composer footer
• Subagent display visual reference
• Subagent stays ungrouped beside reading tools
• Semantic search subagent markdown
• Light-theme approval with a bright accent
• Light-theme syntax, fills, and selection
• Grouped outside-sandbox command approval
• Remote desktop discovered-port list with one selected
• Settings scroll + sticky footer geometry
• Per-model reasoning / temperature / top-p
• Thread switch hydration notice
• Thread switch hydration failure
• Chat layout styling
  _{Static demo of the renderer against a mock API — the browser pane, terminal, and all main-process IPC are stubbed, so it never proves main-process behaviour. Rebuilt whenever a push changes the demo bundle; these links go live once the queued deploy lands, shortly after this comment. Removed when the PR closes.}