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/adapters/__tests__/bestiary-cache-fallback.test.ts

@@ -0,0 +1,95 @@
+import type { Creature } from "@initiative/domain";
+import { creatureId } from "@initiative/domain";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+// Mock idb to reject — simulates IndexedDB unavailable.
+// This must be a separate file from bestiary-cache.test.ts because the
+// module caches the db connection in a singleton; once openDB succeeds
+// in one test, the fallback path is unreachable.
+vi.mock("idb", () => ({
+	openDB: vi.fn().mockRejectedValue(new Error("IndexedDB unavailable")),
+}));
+
+const {
+	cacheSource,
+	isSourceCached,
+	getCachedSources,
+	clearSource,
+	clearAll,
+	loadAllCachedCreatures,
+} = await import("../bestiary-cache.js");
+
+function makeCreature(id: string, name: string): Creature {
+	return {
+		id: creatureId(id),
+		name,
+		source: "MM",
+		sourceDisplayName: "Monster Manual",
+		size: "Small",
+		type: "humanoid",
+		alignment: "neutral evil",
+		ac: 15,
+		hp: { average: 7, formula: "2d6" },
+		speed: "30 ft.",
+		abilities: { str: 8, dex: 14, con: 10, int: 10, wis: 8, cha: 8 },
+		cr: "1/4",
+		initiativeProficiency: 0,
+		proficiencyBonus: 2,
+		passive: 9,
+	};
+}
+
+describe("bestiary-cache fallback (IndexedDB unavailable)", () => {
+	beforeEach(async () => {
+		await clearAll();
+	});
+
+	it("cacheSource falls back to in-memory store", async () => {
+		const creatures = [makeCreature("mm:goblin", "Goblin")];
+		await cacheSource("MM", "Monster Manual", creatures);
+
+		expect(await isSourceCached("MM")).toBe(true);
+	});
+
+	it("isSourceCached returns false for uncached source", async () => {
+		expect(await isSourceCached("XGE")).toBe(false);
+	});
+
+	it("getCachedSources returns sources from in-memory store", async () => {
+		await cacheSource("MM", "Monster Manual", [
+			makeCreature("mm:goblin", "Goblin"),
+		]);
+
+		const sources = await getCachedSources();
+		expect(sources).toHaveLength(1);
+		expect(sources[0].sourceCode).toBe("MM");
+		expect(sources[0].creatureCount).toBe(1);
+	});
+
+	it("loadAllCachedCreatures assembles creatures from in-memory store", async () => {
+		const goblin = makeCreature("mm:goblin", "Goblin");
+		await cacheSource("MM", "Monster Manual", [goblin]);
+
+		const map = await loadAllCachedCreatures();
+		expect(map.size).toBe(1);
+		expect(map.get(creatureId("mm:goblin"))?.name).toBe("Goblin");
+	});
+
+	it("clearSource removes a single source from in-memory store", async () => {
+		await cacheSource("MM", "Monster Manual", []);
+		await cacheSource("VGM", "Volo's Guide", []);
+
+		await clearSource("MM");
+
+		expect(await isSourceCached("MM")).toBe(false);
+		expect(await isSourceCached("VGM")).toBe(true);
+	});
+
+	it("clearAll removes all data from in-memory store", async () => {
+		await cacheSource("MM", "Monster Manual", []);
+		await clearAll();
+
+		const sources = await getCachedSources();
+		expect(sources).toEqual([]);
+	});
+});