refactor(board): delete old board routes, absorb slackHandle into profile PATCH

- Delete server/api/members/me/board.patch.js and server/api/board/suggestions.get.js
- Add boardSlackHandle to memberProfileUpdateSchema; remove boardPrivacy
- profile.patch.js: write boardSlackHandle -> board.slackHandle; drop boardPrivacy
- Remove privacy.board field from Member model
- onboarding/status.get.js: hasProfileTags now requires only craftTags; hasEngagedBoard uses BoardPost.exists
- onboarding/track.post.js: graduation check uses BoardPost.exists instead of board.topics elemMatch
- members/[id].get.js and directory.get.js: reduce board response to slackHandle only; drop connectionTag and peerSupport filters

server/api/members/[id].get.js

@@ -70,21 +70,9 @@ export default defineEventHandler(async (event) => {
     if (isVisible("socialLinks")) filtered.socialLinks = member.socialLinks;
     if (isVisible("craftTags")) filtered.craftTags = member.craftTags;
 
-    if (isVisible("board")) {
-      const board = member.board || {};
-      filtered.board = {
-        topics: board.topics,
-        offerPeerSupport: board.offerPeerSupport,
-        availability: board.availability,
-        details: board.details,
-        // Contact-in-place: surface the handle + personal message only when
-        // the member has explicitly opted into peer support.
-        ...(board.offerPeerSupport && {
-          slackHandle: board.slackHandle,
-          personalMessage: board.personalMessage,
-        }),
-      };
-    }
+    filtered.board = {
+      slackHandle: member.board?.slackHandle,
+    };
 
     return { member: filtered };
   } catch (error) {