[v1.0] Pawnly MVP — solidify play vs Stockfish, lessons, puzzles, scan trainer

[Jonathangadeaharder]

v1.0 bar — Pawnly (formerly Chess)

"Clean v1.0": current chess app (play vs Stockfish, lessons, puzzles, scan trainer) works 100%. Solidify, harden tests. No growth.

Confirmed feature surface for v1.0

• Play vs Stockfish (multiple difficulty levels)
• Lessons (Learn screen with timeline)
• Puzzles (Train screen with grid + solving overlay)
• Scan trainer (scan-positions practice)
• Onboarding flow (5-step)
• Profile + stats + achievements
• Local-first sync via Supabase

Acceptance for v1.0

• Every screen above has Vitest unit coverage ≥85% on its .svelte.ts modules
• Playwright e2e covers every route happy-path
• Stockfish worker integration robust (no leaks; cap depth)
• Visual regression suite green
• PWA installable + offline shell loads
• Telemetry calls go through a single abstraction
• Pawnly brand consistent (mascot, palette, wordmark) across every screen

Out of scope (future)

Multiplayer, opening repertoire builder, endgame tablebase, rated games → all future/* branches.