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>

frontend/src/views/settings/settingsNav.js

@@ -22,6 +22,7 @@ export const settingsGroups = [
       { to: '/settings/relationshiptypes', icon: Link, title: 'Relationship Types', description: 'Manage asset relationship types (Controls, Contains...) + colors' },
       { to: '/settings/assettypes', icon: Palette, title: 'Asset Type Colors', description: 'Map colors for the top-level asset categories' },
       { to: '/settings/customfields', icon: SlidersHorizontal, title: 'Custom Fields', description: 'Define extra attributes per asset type (shown on detail + forms)' },
+      { to: '/settings/supportteams', icon: Users, title: 'Support Teams', description: 'Application support teams and their contacts (ServiceNow group links)' },
     ],
   },
   {