Add application support teams with contacts

Replaces the legacy supportteams/appowners pair: supportteams
(teamname unique, teamurl ServiceNow link) + supportteamcontacts
(multiple named contacts with SSO per team, the people you reach out
to), applications.supportteamid intact. Migration 7d18 migrates each
legacy team owner into a contact, drops appowners, and has a validated
downgrade. New /api/supportteams CRUD (admin writes, import-mode
timestamps, teamname lookup), Support card on application detail,
contacts column on the list, and a settings management page.
IMPORT-API.md mapping updated to the concrete endpoints.

658 tests pass; live dev migration applied (24 teams / 24 contacts);
fresh-install and downgrade round-trips verified on scratch DBs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -12,6 +12,19 @@ ADR-007 and ADR-002.
 
 ### Added
 
+- Application support teams with contacts, replacing the legacy
+  supportteams/appowners pair. New core `supportteamcontacts` table (multiple
+  named contacts per team, ordered by `sortorder`); `supportteams` keeps
+  `teamname` (now unique) and `teamurl` (a ServiceNow group deep link) and
+  sheds the single-owner `appownerid` FK. New core blueprint at
+  `/api/supportteams` (team + nested contact CRUD, admin-gated; `?teamname`
+  exact-match lookup for import; delete a team 409s while any application still
+  references it). Migration `7d18_supportteamcontacts` migrates each legacy
+  team's app owner into one contact. Application payloads now flatten
+  `supportteamname`, `teamurl`, and the team's active `contacts`; a Support
+  card on the application detail page and a new `settings/supportteams`
+  management page render them.
+
 - Import mode: a complete, idempotent HTTP migration surface so a script or LLM
   can import the classic ASP shopdb through the API alone (no direct DB writes).
   - Contract surface (plugin contract bumped 0.7.0 -> 0.8.0, additive): new