Bootstrap project and safe work-item workflow

delivery_backlog/stories/US01-05-thumbnail-service.md

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+# US01-05 — Generate and Serve Managed Thumbnails
+
+Epic: [E01](../E01-shared-identity-inventory.md)
+
+As a reviewer, I want safe, correctly oriented previews so I can compare photos without
+exposing arbitrary filesystem paths.
+
+## Acceptance criteria
+
+- Donor decode, orientation, resize, and HEIC behavior is reused where compatible.
+- Thumbnails are requested by asset ID, cached atomically, quota-managed, and
+  invalidated when source identity changes.
+- Corrupt, oversized, missing, and unsupported inputs produce bounded typed errors.
+- Requests cannot escape configured roots or access excluded paths.
+
+## Automated tests
+
+- Golden tests assert orientation, dimensions, transparency handling, and cache keys.
+- Integration tests cover concurrent generation, corruption, invalidation, eviction,
+  and path attacks.
+
+## Dependencies
+
+- US01-03