rename communityEcology → board across backend

Model, schemas, API routes, activity log, and all server handlers
updated. Old ecology/ and community-ecology routes removed, new
board/ routes added. Tests updated and new board-suggestions tests
written (10 cases).

tests/server/api/events-recommended.test.js

@@ -39,7 +39,7 @@ function makeMember(overrides = {}) {
   return {
     _id: 'member-1',
     craftTags: [],
-    communityEcology: { topics: [] },
+    board: { topics: [] },
     ...overrides
   }
 }
@@ -82,9 +82,9 @@ describe('GET /api/events/recommended', () => {
     )
   })
 
-  it('returns events matching cooperative tags from communityEcology.topics', async () => {
+  it('returns events matching cooperative tags from board.topics', async () => {
     const member = makeMember({
-      communityEcology: {
+      board: {
         topics: [
           { tagSlug: 'revenue-sharing', state: 'interested' },
           { tagSlug: 'co-op-governance', state: 'help' }