refactor(peer-support): delete provably dead code (Phase 1)

The Skills Exchange + Peer Support feature was replaced by Community
Connections on 2026-04-05, but several files and code paths were left
in place as backward-compat. None are reachable from the live UI:

- usePeerSupport.js composable: not imported anywhere
- PeerSupportBadge.vue: not imported anywhere
- peer-support.vue: stub redirect with no incoming links
- /api/peer-support.get.js: only consumed by usePeerSupport
- /api/members/me/peer-support.patch.js: same
- profile.patch.js offering/lookingFor write branches: profile form
  no longer sends these fields (only writes communityConnections.*)
- PEER_SUPPORT_ENABLED/DISABLED activity types and renderers: only
  written by the deleted peer-support.patch endpoint. The activityText
  formatter has a fallback for unknown types so existing records
  still display ("peer support enabled" with a generic icon).

Tests updated to drop peerSupportUpdateSchema coverage and the
offering/lookingFor passthrough assertion.

schemas.js cleanup deferred — concurrent communityConnections →
communityEcology rename is in flight in the working tree.

server/utils/activityLog.js

@@ -5,8 +5,6 @@ export const ACTIVITY_TYPES = {
   EVENT_REGISTERED: 'event_registered',
   EVENT_CANCELLED: 'event_cancelled',
   EVENT_WAITLISTED: 'event_waitlisted',
-  PEER_SUPPORT_ENABLED: 'peer_support_enabled',
-  PEER_SUPPORT_DISABLED: 'peer_support_disabled',
   CIRCLE_CHANGED: 'circle_changed',
   CONTRIBUTION_CHANGED: 'contribution_changed',
   EMAIL_CHANGED: 'email_changed',
@@ -29,8 +27,6 @@ export const ACTIVITY_TYPE_DEFAULTS = {
   event_registered: 'public',
   event_cancelled: 'member',
   event_waitlisted: 'member',
-  peer_support_enabled: 'public',
-  peer_support_disabled: 'member',
   circle_changed: 'member',
   contribution_changed: 'member',
   email_changed: 'member',