fix: make guardian names deterministic per floor instead of using Math.random()

- generateGuardianName() now takes a floor parameter and uses floor % prefixes.length for deterministic prefix selection
- generateComboGuardianName() now takes a floor parameter and uses (floor + i) % prefixes.length for each element
- getGuardianForFloor() passes floor to generateGuardianName for static guardians with empty names
- getExtendedGuardian() passes floor to generateComboGuardianName for combo guardians
- Removes dependency on Math.random() → names are stable across ticks/refreshes

Fixes #161

docs/project-structure.txt

@@ -213,6 +213,7 @@ Mana-Loop/
 │       │   │   ├── floor-utils.test.ts
 │       │   │   ├── floor-utils.upgraded.test.ts
 │       │   │   ├── formatting.test.ts
+│       │   │   ├── guardian-names.test.ts
 │       │   │   ├── mana-utils.test.ts
 │       │   │   ├── pact-utils.test.ts
 │       │   │   ├── regression-fixes.test.ts