fix: address CodeRabbit review issues

- redis-handler: add TLS_CA and USERNAME env support matching core client
- connection.ts: fix Boolean() truthy bug (CI="false" was disabling Redis)
- channel.ts: add in-memory lock for single-instance fallback mode
- channel-subscription-tracker: lazy-init subscriber client
- board.ts: invalidate user cache on board delete for home-board users
- .env.example: document REDIS_CACHE_DB vs DATABASE_INDEX collision risk
- CLI docs: fix docker exec command (remove /bin/bash prefix)
- Docker docs: fix docker rm -f and docker ps -a for stopped containers

packages/api/src/router/board.ts

@@ -648,8 +648,16 @@ export const boardRouter = createTRPCRouter({
         columns: { name: true },
       });
 
+      const affectedUsers = await ctx.db.query.users.findMany({
+        columns: { id: true },
+        where: eq(users.homeBoardId, input.id),
+      });
+
       await ctx.db.delete(boards).where(eq(boards.id, input.id));
 
+      for (const user of affectedUsers) {
+        invalidateUserCache(user.id);
+      }
       invalidateBoardCache(input.id, existingBoard?.name);
     }),
   setHomeBoard: protectedProcedure