Add Pathfinder 2e game system mode

Implements PF2e as an alternative game system alongside D&D 5e/5.5e.
Settings modal "Game System" selector switches conditions, bestiary,
stat block layout, and initiative calculation between systems.

- Valued conditions with increment/decrement UX (Clumsy 2, Frightened 3)
- 2,502 PF2e creatures from bundled search index (77 sources)
- PF2e stat block: level, traits, Perception, Fort/Ref/Will, ability mods
- Perception-based initiative rolling
- System-scoped source cache (D&D and PF2e sources don't collide)
- Backwards-compatible condition rehydration (ConditionId[] → ConditionEntry[])
- Difficulty indicator hidden in PF2e mode (excluded from MVP)

Closes dostulata/initiative#19

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/application/src/__tests__/use-cases.test.ts

@@ -292,9 +292,9 @@ describe("toggleConditionUseCase", () => {
 		);
 
 		expect(isDomainError(result)).toBe(false);
-		expect(requireSaved(store.saved).combatants[0].conditions).toContain(
-			"blinded",
-		);
+		expect(requireSaved(store.saved).combatants[0].conditions).toContainEqual({
+			id: "blinded",
+		});
 	});
 
 	it("returns domain error for unknown combatant", () => {