docs(clone-app): game-variant prose parity + normalize extract-logic mode

Whole-branch review follow-ups: append game rules/formulas to the build-spec
Game-variant §3 bullet for parity with spec §4.3; chmod extract-logic.py
0755→0644 to match sibling python scripts (all run via python3, never exec'd).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

plugins/clone-app/skills/clone-app/references/clone-build-spec-template.md

@@ -60,7 +60,8 @@ Absolute paths to: `design-tokens.json`, `design-digest.md`, `screenshots/`,
 Replace these sections:
 - **§2 Design system** → art style + UI atlas inventory; palette from sprites.
 - **§3 Screen-by-screen** → **scene/prefab-by-scene** spec (from `unity-digest.md`):
-  each scene's objects, UI canvas, transitions; matching screenshot.
+  each scene's objects, UI canvas, transitions; matching screenshot;
+  + game rules / formulas (from `unity-digest.md`).
 - **§5 API contract** → **netcode**: backend (Photon/PlayFab/Mirror/custom),
   message types, sync model (from the IL2CPP/Mono type model).
 - **§7 Asset inventory** → `$WORK/game-assets/` manifest (sprites, atlases,