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/wiki-recommended.test.js

@@ -37,7 +37,7 @@ function makeMember(overrides = {}) {
   return {
     _id: 'member-1',
     craftTags: [],
-    communityEcology: { topics: [] },
+    board: { topics: [] },
     ...overrides
   }
 }