The update/delete handlers for medications and appointments took the
auth Claims but never used them — any authenticated user could update
or delete any other user's records by id (an IDOR). Same gap on
log_dose (could skew another's adherence stats) and get_adherence
(leaked dose history).
Fix: each affected handler now looks up the item first and confirms
user_id == claims.sub before mutating/returning. Mismatches return 404
(not 403) to avoid leaking the existence of other users' records.
Recipients of shared profiles remain read-only per the ADR — writes
stay owner-only.
Covered handlers:
- update_medication, delete_medication, log_dose, get_adherence
- update_appointment, delete_appointment
health_stats update/delete were already checking user_id == claims.sub
(unaffected).
New ownership_tests.rs: cross-user update/delete/log-dose/adherence all
404; the legitimate owner can still do all of the above.
Verification: cargo build/clippy (-D warnings)/fmt clean; existing
tests unaffected (they operate as the same user that created the data).
Closes#12.
