Add command palette feature tip

[brennanb2025]

Summary

• Adds a concrete in-app feature tip for the Cmd+J command palette, teaching users they can jump across worktrees, settings, tabs, and quick actions from one search surface.
• Renders the live, platform-correct binding via useShortcutKeys('worktree.palette') so the keycap cue stays accurate after a rebind (and shows Ctrl+Shift+J on Linux/Windows), with the description pointing to Settings for rebinding.
• Hand-authored an Orca-style CSS/keyframes animation (keypress cue → palette entrance → selection sweep across a worktree, the Shortcuts setting, and a quick action). No runtime GIF/video.
• Passive education tip: single Got it acknowledgement CTA, no secondary "Maybe Later". Priority sits just after the Orca CLI tip.

Test plan

• pnpm exec vitest run --config config/vitest.config.ts src/shared/feature-tips.test.ts src/renderer/src/components/feature-tips/feature-tip-modal-state.test.ts src/renderer/src/components/feature-tips/feature-tip-startup-gate.test.ts
• Typecheck (tsgo -p config/tsconfig.tc.web.json) and oxlint on changed files
• Animation + modal composition verified via Playwright-screenshotted mock mirroring the React port's classes/timing. Live Electron renderer not spun up to avoid disturbing concurrent dev sessions.

Generated after feature-tip candidate review.

Made with Orca 🐋