docs: reorganize TODO, DONE, and BACKLOG task tracking

.github/instructions/TODO.md

@@ -1,3 +1,29 @@
 # TODO
 
 > Completed tasks moved to [DONE](./DONE.md). Remaining tasks in [BACKLOG](./BACKLOG.md).
+
+## R2 Data Retention
+
+- [ ] Adjust internal data retention for R2: remove folders /hls/r-{ISOTIME} after next run, keep only the last 2 runs or max. 10GB of data
+
+## Frontend Tests
+
+### User Frontend
+
+- [ ] Test coverage for all critical frontend components and interactions
+- [ ] Add code coverage reporting and enforce minimum coverage threshold in CI/CD pipeline
+- [ ] Document test cases and expected outcomes
+
+### Admin Frontend
+
+- [ ] Test coverage for all critical admin UI components and interactions
+- [ ] Add code coverage reporting and enforce minimum coverage threshold in CI/CD pipeline
+- [ ] Document test cases and expected outcomes
+
+## Backend Integration Tests
+
+### Cloudflare R2
+
+- [ ] Test retrieval of segments and manifests from R2 via Cloudflare edge
+- [ ] Validate cache hit/miss behavior and performance metrics
+- [ ] Validate edge cache hit/miss behavior with repeat requests — script `scripts/validate-edge-cache.sh` created