feat!: rewrite on Svelte 5, drop Phaser

Replace Phaser 3 with Svelte 5 as the rendering and UI layer. The
framework-agnostic core (level parser, board model, progress store,
microban level data) moves from src/game/core → src/lib/core with zero
code changes. Scenes and the hand-rolled button factory are gone; in
their place:

- src/App.svelte            root router (menu / levels / game)
- src/views/MenuView        title + play + progress + hints
- src/views/LevelSelectView paginated 5x4 grid with native <button>s
- src/views/GameView        owns BoardModel, handles input, HUD, win
- src/views/Board           purely presentational DOM renderer
- src/views/AppButton       shared themed wrapper for native <button>
- src/app.css               Nord palette ported to CSS variables

GameView uses a non-reactive BoardModel ref and syncs plain snapshot
fields (player, boxes, moves, won) into $state after every mutation —
Board consumes only plain props, so Svelte reactivity stays predictable
and the core class stays framework-agnostic. GameView is keyed on
levelIndex in App, so changing level remounts with fresh state.

Native <button> everywhere kills the click-hitbox class of bugs.
Animations are now CSS transform transitions (110ms) instead of tweens.

Bundle shrinks from ~1.5 MB Phaser to ~65 kB JS / 23 kB gzipped — about
60x smaller. Removed: phaser, terser, src/game, log.js (analytics
ping), phasermsg vite plugin, manual Phaser chunks, terser config,
public/style.css. Scripts simplified to dev/build.

Docs updated: codebase summary, architecture, code standards,
changelog, roadmap, README.

README.md

@@ -1,6 +1,6 @@
 # Sokoban
 
-My from-scratch Sokoban game, built with Phaser 3 and Vite. The engine, UI, level parser, and progression system are all my own implementation. The puzzle layouts themselves come from David W. Skinner's freely distributable **Microban** set — I'm not reusing any of his code, only his level designs.
+My from-scratch Sokoban game, built with **Svelte 5** and **Vite**. The engine, UI, level parser, and progression system are all my own implementation. The puzzle layouts themselves come from David W. Skinner's freely distributable **Microban** set — I'm not reusing any of his code, only his level designs.
 
 Play: [https://tiennm99.github.io/sokoban/](https://tiennm99.github.io/sokoban/)
 
@@ -18,8 +18,6 @@ Play: [https://tiennm99.github.io/sokoban/](https://tiennm99.github.io/sokoban/)
 npm install
 npm run dev          # dev server on http://localhost:8080
 npm run build        # production build
-npm run dev-nolog    # dev without the analytics ping
-npm run build-nolog  # build without the analytics ping
 ```
 
 ## Project layout
@@ -35,7 +33,7 @@ See [`docs/codebase-summary.md`](docs/codebase-summary.md).
 ## Credits
 - Puzzle layouts: **Microban** level set by David W. Skinner (April 2000). Freely distributable with credit. Original site: http://users.bentonrea.com/~sasquatch/sokoban/
 - Game code: tiennm99 (with AI pair-programming from Claude).
-- Engine: [Phaser 3](https://phaser.io/).
+- Framework: [Svelte 5](https://svelte.dev/) on top of [Vite](https://vite.dev/).
 
 ## License
 - Source code: see [`LICENSE`](LICENSE).