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/components/source-fetch-prompt.tsx

@@ -1,9 +1,6 @@
 import { Download, Loader2, Upload } from "lucide-react";
 import { useId, useRef, useState } from "react";
-import {
-	getDefaultFetchUrl,
-	getSourceDisplayName,
-} from "../adapters/bestiary-index-adapter.js";
+import { useAdapters } from "../contexts/adapter-context.js";
 import { useBestiaryContext } from "../contexts/bestiary-context.js";
 import { Button } from "./ui/button.js";
 import { Input } from "./ui/input.js";
@@ -17,9 +14,12 @@ export function SourceFetchPrompt({
 	sourceCode,
 	onSourceLoaded,
 }: Readonly<SourceFetchPromptProps>) {
+	const { bestiaryIndex } = useAdapters();
 	const { fetchAndCacheSource, uploadAndCacheSource } = useBestiaryContext();
-	const sourceDisplayName = getSourceDisplayName(sourceCode);
-	const [url, setUrl] = useState(() => getDefaultFetchUrl(sourceCode));
+	const sourceDisplayName = bestiaryIndex.getSourceDisplayName(sourceCode);
+	const [url, setUrl] = useState(() =>
+		bestiaryIndex.getDefaultFetchUrl(sourceCode),
+	);
 	const [status, setStatus] = useState<"idle" | "fetching" | "error">("idle");
 	const [error, setError] = useState<string>("");
 	const fileInputRef = useRef<HTMLInputElement>(null);