feat: show mining frame toast on OSD and speed up stats session deletes

- Flash mined-frame screenshot as in-overlay image toast for OSD card notifications
- Batch cover art from stored DB blobs via POST /api/stats/covers (no extra AniList fetches)
- Show delete progress toast on stats home and sessions pages
- Refresh only affected rollups on session delete instead of full rebuild
- Rebuild lifetime summaries with aggregate SQL CTEs instead of per-session loop

stats/src/styles/globals.test.ts

@@ -1,5 +1,6 @@
 import assert from 'node:assert/strict';
 import { readFileSync } from 'node:fs';
+import test from 'node:test';
 import { fileURLToPath } from 'node:url';
 
 const css = readFileSync(fileURLToPath(new URL('./globals.css', import.meta.url)), 'utf8');