feat: add multi-strategy version fetchers, disable auto-fetch by default

- Add 4 version-fetch strategies (UpToDateCheck API, Store Page Scrape,
  Community Hub Scrape, Store API Heuristic) — no Steam API key needed
- Create orchestrator that tries all strategies, prefers named version
  over build ID
- Add test page at /test-version-fetchers for comparing strategies
- Add standalone /api/version-test endpoint (direct Steam App ID, no DB)
- Update /api/games/:id/steamdb-version to use new strategies
- Disable auto-fetch on submit page by default (NEXT_PUBLIC_VERSION_AUTO_FETCH=true to enable)
- SteamDB scraping blocked by Cloudflare; strategies preserved for later enablement

lib/version-fetchers/types.ts

@@ -0,0 +1,18 @@
+/** Result from a single version-fetch strategy */
+export interface VersionFetchResult {
+  /** Human-readable version string like "1.2.3" or "Patch 4.0" */
+  versionString: string | null
+  /** Numeric build ID from Steam */
+  buildId: string | null
+  /** Which strategy produced this result */
+  source: string
+  /** Whether the strategy succeeded (even if partial — e.g. buildId only) */
+  success: boolean
+  /** Error message if strategy failed completely */
+  error?: string
+}
+
+/** A version-fetch strategy function */
+export type VersionFetchStrategy = (
+  steamAppId: number,
+) => Promise<VersionFetchResult>