Introduce adapter injection and migrate test suite

Replace direct adapter/persistence imports with context-based injection
(AdapterContext + useAdapters) so tests use in-memory implementations
instead of vi.mock. Migrate component tests from context mocking to
AllProviders with real hooks. Extract export/import logic from ActionBar
into useEncounterExportImport hook. Add bestiary-cache and
bestiary-index-adapter test suites. Raise adapter coverage thresholds
(68→80 lines, 56→62 branches).

77 test files, 891 tests, all passing.

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

apps/web/src/hooks/use-player-characters.ts

@@ -7,14 +7,7 @@ import {
 import type { PlayerCharacter, PlayerCharacterId } from "@initiative/domain";
 import { isDomainError, playerCharacterId } from "@initiative/domain";
 import { useCallback, useEffect, useRef, useState } from "react";
-import {
-	loadPlayerCharacters,
-	savePlayerCharacters,
-} from "../persistence/player-character-storage.js";
-
-function initializeCharacters(): PlayerCharacter[] {
-	return loadPlayerCharacters();
-}
+import { useAdapters } from "../contexts/adapter-context.js";
 
 let nextPcId = 0;
 
@@ -32,14 +25,16 @@ interface EditFields {
 }
 
 export function usePlayerCharacters() {
-	const [characters, setCharacters] =
-		useState<PlayerCharacter[]>(initializeCharacters);
+	const { playerCharacterPersistence } = useAdapters();
+	const [characters, setCharacters] = useState<PlayerCharacter[]>(() =>
+		playerCharacterPersistence.load(),
+	);
 	const charactersRef = useRef(characters);
 	charactersRef.current = characters;
 
 	useEffect(() => {
-		savePlayerCharacters(characters);
-	}, [characters]);
+		playerCharacterPersistence.save(characters);
+	}, [characters, playerCharacterPersistence]);
 
 	const makeStore = useCallback((): PlayerCharacterStore => {
 		return {