[feature] Quick-search command palette (press /)

## Summary
Jump to any stock by symbol or name from anywhere with a keyboard shortcut.

## Proposed change
Press `/` to open an overlay input; typing filters the 10 stocks; Enter navigates to `/stock/[symbol]`. Esc closes.

## Affected area
`components/finance/command-palette.tsx` (new), wired into `app/layout.tsx`.

## Acceptance criteria
- [ ] Opens on `/`, closes on Esc, fully keyboard navigable
- [ ] Reduced-motion respected; no hydration mismatch

Start by reading app/layout.tsx and the planned components/finance/command-palette.tsx entry point, then inspect how the 10 stocks and /stock/[symbol] navigation are represented. Done means the palette opens with /, filters by symbol or name, navigates on Enter, closes with Esc, supports keyboard navigation, respects reduced motion, and avoids hydration mismatches.

Written by the indexing model from the issue text.