Switch image attachments to persisted ID-based paths

- add attachment store helpers for IDs, route paths, and file resolution
- stop projection pipeline from mutating/storing data URLs; keep attachment metadata unchanged
- update Codex send/branch generation flows and tests to resolve images via attachment IDs
585031572fJulius Marminge committed on 3/1/2026, 9:42:02 AMparentcd732a2
18 files changedLine totals unavailable