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>

apps/web/src/components/__tests__/source-fetch-prompt.test.tsx

@@ -6,6 +6,7 @@ import userEvent from "@testing-library/user-event";
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { createTestAdapters } from "../../__tests__/adapters/in-memory-adapters.js";
 import { AdapterProvider } from "../../contexts/adapter-context.js";
+import { RulesEditionProvider } from "../../contexts/rules-edition-context.js";
 import { SourceFetchPrompt } from "../source-fetch-prompt.js";
 
 const MONSTER_MANUAL_REGEX = /Monster Manual/;
@@ -36,12 +37,14 @@ function renderPrompt(sourceCode = "MM") {
 			code === "MM" ? "Monster Manual" : code,
 	};
 	const result = render(
-		<AdapterProvider adapters={adapters}>
-			<SourceFetchPrompt
-				sourceCode={sourceCode}
-				onSourceLoaded={onSourceLoaded}
-			/>
-		</AdapterProvider>,
+		<RulesEditionProvider>
+			<AdapterProvider adapters={adapters}>
+				<SourceFetchPrompt
+					sourceCode={sourceCode}
+					onSourceLoaded={onSourceLoaded}
+				/>
+			</AdapterProvider>
+		</RulesEditionProvider>,
 	);
 	return { ...result, onSourceLoaded };
 }