feat(levels): ship the full 155-puzzle Microban set

Expand the level data from the first 100 Microban layouts to the complete
set, up through the two oversized finale mazes ("Take the long way home"
and "The Dungeon"). Responsive tile sizing already handles the large
grids — no rendering changes needed.

Update credit language in README, PDR, changelog, roadmap, codebase
summary, menu subtitle, and the data file header to reflect the full
set. Credit for David W. Skinner's layouts remains prominent; ownership
of the engine, UI, parser, and progression code stays explicit.

Verified all 155 layouts parse cleanly, have a player, matching box/goal
counts, and none start already solved.

docs/codebase-summary.md

@@ -7,7 +7,7 @@ src/
 └── game/
     ├── main.js                     # Phaser Game config + scene registration
     ├── data/
-    │   └── microban-levels.js      # 100 XSB level strings
+    │   └── microban-levels.js      # 155 XSB level strings (full Microban set)
     ├── core/
     │   ├── level-parser.js         # XSB text → {walls, targets, boxes, player, floors}
     │   ├── board-model.js          # Pure game state + move/undo/win logic