feat(documentation-dialog): collapsible sections for docs content

[alpha5611331]

Summary

• Added shadcn Accordion component (src/renderer/components/ui/accordion.tsx)
• Refactored DocumentationDialog so "Lost the window?" and "Hotkeys" render as collapsible accordion sections instead of always-expanded text blocks, for a cleaner, more professional and scannable dialog
• "Hotkeys" is expanded by default since it's the most-referenced section; "Lost the window?" starts collapsed

Closes #94

Test plan

• pnpm exec tsc -b — passes
• pnpm exec eslint on changed files — passes
• pnpm build — production build succeeds
• Manual click-through in the running app (not exercised in this sandbox — no display/Playwright available here; please verify visually before merge)

[gitar-bot]

Code Review ✅ Approved

Adds collapsible accordion sections to the documentation dialog using a new shadcn component, improving content scannability. No issues found.

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[anton-karlovskiy]

LGTM

[chmm195]

Looks good to me.

[kevinkamto]

Good job 👍