Polish Flow Reader product experience

[M3RCU3Y]

What changed

• upgraded the landing experience with a stronger visual hierarchy, deeper surfaces, and a more intentional reading workspace
• refined the Flow Reader mark and ambient backdrop
• rebuilt library cards so selection and deletion work cleanly with keyboard, touch, and pointer input
• improved reader-mode tab keyboard behavior and focus handling
• tightened app metadata and PWA cache behavior
• removed stale Gemini build configuration
• added non-deploying CI for pull requests and feature branches
• documented the remaining UX, reliability, privacy, architecture, and testing work in docs/UX_AUDIT.md

Why

The reader already has substantial functionality, but the product surface felt less trustworthy and coherent than the underlying feature set. This pass focuses on product polish and interaction quality without rewriting the RSVP/Bionic reading engine or changing persistence semantics.

Safety

This PR targets main but remains a draft. The branch is agent/flow-reader-product-polish; no commits were pushed directly to main. The existing GitHub Pages deployment workflow only deploys pushes to main.

Validation

Branch CI runs:

• npm ci
• npm run check
• npm run build

The latest branch CI completed successfully before opening this draft PR.

Follow-up

The highest-value next pass is bundling current CDN runtime dependencies, then splitting the oversized app/import orchestration components and adding browser-level regression coverage.

[M3RCU3Y]

Maintenance follow-up added on this existing polish branch: added the MIT license, raised the runtime/CI floor to Node 24, modernized the Vite toolchain to Vite 8 + the Vite 8-compatible PWA plugin + TypeScript 7, and regenerated the npm lockfile from a clean dependency graph. No GitHub Release was added; Flow Reader remains a GitHub Pages project.