Improve UI reliability and end-to-end coverage

[nearbycoder]

What changed

• Refined the landing, authentication, onboarding, dashboard, profile, and public profile experiences while preserving the kinetic editorial design.
• Added progressive disclosure for large link collections, touch-accessible actions, global mutation feedback, and stronger keyboard/accessibility behavior.
• Fixed pre-hydration auth submission leakage, stale link-edit state, profile form clobbering, sign-out navigation, username availability races, and SSR API origin routing on non-default ports.
• Added a complete Playwright creator journey covering account creation, onboarding, link and section management, uploads, public rendering, click analytics, password changes, re-authentication, and deletion.

Why

The app needed a complete UI and functional reliability pass. Stress-testing realistic large profiles and full authenticated workflows exposed several state synchronization, touch interaction, and environment-routing defects that were not covered by the original public-page-only test suite.

Impact

Creators get clearer feedback, reliable edits, usable large collections, better mobile controls, and safer authentication behavior. The expanded end-to-end coverage now verifies the primary product journey across the UI, API, database, storage, and analytics boundaries.

Validation

• Biome check: passed
• TypeScript type-check: passed
• Unit tests: 31 passed
• Playwright tests: 3 passed
• Production build: passed
• Desktop and 390px mobile browser verification: passed with no runtime overlay or horizontal overflow