feat(playout): replace time-based R2 retention with run-count and size caps

.env.example

@@ -8,7 +8,8 @@ R2_SECRET_ACCESS_KEY=your-r2-secret-key
 R2_BUCKET_NAME=linearvoid-media
 R2_ENDPOINT=https://your-account-id.r2.cloudflarestorage.com
 R2_REGION=auto
-R2_SEGMENT_RETENTION_HOURS=24
+R2_KEEP_RUNS=2
+R2_MAX_RETENTION_BYTES=10737418240
 
 # Cloudflare (for custom domain, cache rules, Workers if used)
 CLOUDFLARE_API_TOKEN=your-cloudflare-api-token