fix: resolve 4 tag-blocking issues for v0.1.0

- README/CONTRIBUTING quick start: add UPTOP_ADMIN_KEY so SSH works on
  fresh DB, fix single-file go run path that doesn't compile
- apply --dry-run: assign placeholder IDs for new alerts and groups so
  resolveAlertID succeeds when monitors reference not-yet-created alerts
- deploy/*.yml: switch user-facing compose files from broken build
  context to image: lerkolabs/uptop:latest, fix dev context to ..

deploy/docker-compose.cluster.yml

@@ -3,7 +3,7 @@ services:
   # LEADER NODE
   # -------------------------
   leader:
-    build: .
+    image: lerkolabs/uptop:latest
     container_name: uptop-leader
     ports:
       - "23234:23234" # SSH
@@ -38,7 +38,7 @@ services:
   # FOLLOWER NODE
   # -------------------------
   follower:
-    build: .
+    image: lerkolabs/uptop:latest
     container_name: uptop-follower
     ports:
       - "23233:23234" # SSH (Mapped to different host port)