Small fixes from the architecture review.
- A
-- foreign_keys: offmigration runsforeign_key_checkinside its own transaction, before commit, so a violation rolls the migration back; the error names the table and rowid. - The web pin and watch buttons dispatch through
repo pin/unpinandrepo watch/mute/unwatch, so refusals reach the viewer and the writes are audited. The watch button cycles default, watching, muted. - The login-link response sends
Cache-Control: no-store. - API, Parity and Threat-Model wiki pages corrected; CHANGELOG.
Stacked on !492 (cli-ux-fixes).
Closes #261