update .drone.yml to add pull request check and separate deployment pipeline

.drone.yml

@@ -1,6 +1,26 @@
 kind: pipeline
 type: kubernetes
-name: default
+name: pr-check
+trigger:
+  event:
+    - pull_request
+
+steps:
+  - name: build-angular
+    image: node:22-alpine
+    commands:
+      - npm ci
+      - npm run build
+
+---
+kind: pipeline
+type: kubernetes
+name: deploy
+trigger:
+  branch:
+    - main
+  event:
+    - push
 
 steps:
   - name: build-angular