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/__tests__/encounter-reducer.test.ts

@@ -10,19 +10,9 @@ import {
 	isDomainError,
 	playerCharacterId,
 } from "@initiative/domain";
-import { describe, expect, it, vi } from "vitest";
+import { describe, expect, it } from "vitest";
 import { type EncounterState, encounterReducer } from "../use-encounter.js";
 
-vi.mock("../../persistence/encounter-storage.js", () => ({
-	loadEncounter: vi.fn().mockReturnValue(null),
-	saveEncounter: vi.fn(),
-}));
-
-vi.mock("../../persistence/undo-redo-storage.js", () => ({
-	loadUndoRedoStacks: vi.fn().mockReturnValue(EMPTY_UNDO_REDO_STATE),
-	saveUndoRedoStacks: vi.fn(),
-}));
-
 function emptyState(): EncounterState {
 	return {
 		encounter: {