test(ui): add command search stories

[Astro-Han]

Summary

Adds Storybook state coverage for the command palette and content search modal as the PR4 slice of the #390 keyboard/modal family work.

Why

Part of #390.

Scope

Changed:

• Adds desktop renderer stories to the Storybook glob.
• Adds command/search stories covering command palette grouped, empty, disabled, keyboard-focused, loading, results, error, and privacy-blocked states.
• Adds search modal stories covering empty, loading, results, no-results, error, and privacy-blocked states.
• Adds a narrow injectable search deps seam for CommandPalette stories while keeping the live preload bridge as the default.
• Extends the Storybook baseline contract for PR4 coverage.

Not included:

• Visual polish or CSS changes.
• Settings / PR5 story coverage.
• Runtime, storage, Electron main, or preload behavior changes.

Verification

• npm run -w @maka/desktop build:main && node --test apps/desktop/dist/main/tests/storybook-baseline-contract.test.js
• npm run -w @maka/desktop build-storybook
• npm run typecheck
• npm run -w @maka/desktop build
• npm run -w @maka/desktop test
• Storybook dev index check: 14 Product/Command Search stories registered on local port 6007

User-facing impact

No runtime user-facing change. Storybook-only state coverage for review before visual polish.

Reviewer notes

The command palette seam is intentionally narrow: stories can inject search deps, while production still defaults to window.maka.search.thread through the existing hook.