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.

app/utils/activityText.js

@@ -23,16 +23,6 @@ const formatters = {
     link: null,
     linkText: null
   }),
-  peer_support_enabled: (m) => ({
-    text: m.topics?.length
-      ? `Enabled peer support (${m.topics.join(', ')})`
-      : 'Enabled peer support',
-    icon: 'i-lucide-users'
-  }),
-  peer_support_disabled: () => ({
-    text: 'Disabled peer support',
-    icon: 'i-lucide-users'
-  }),
   circle_changed: (m) => ({
     text: `Changed circle from ${circleLabel(m.from)} to ${circleLabel(m.to)}`,
     icon: 'i-lucide-refresh-cw'