ci: serialize builds for low-memory Pi runner

Cap MSBuild to one node and Angular to one worker so api/shop/admin
fit under the 2GiB Drone step limit (slower, less OOM).

Co-authored-by: Cursor <cursoragent@cursor.com>

.drone.yml

@@ -7,6 +7,8 @@
 # First-time host setup:
 #   git clone ssh://git@git.zea.lt:2222/miczek/iled-shop.git $DEPLOY_PATH
 #   cd $DEPLOY_PATH/docker && cp .env.example .env  # then edit secrets
+#
+# Pi note: steps serialize workers so builds fit under DRONE_MEMORY_LIMIT (~2GiB).
 
 kind: pipeline
 type: docker
@@ -25,24 +27,38 @@ concurrency:
 steps:
   - name: api
     image: mcr.microsoft.com/dotnet/sdk:10.0
+    environment:
+      # One MSBuild node; disable node reuse — lower peak RAM on 4GB Pi
+      DOTNET_CLI_TELEMETRY_OPTOUT: "1"
+      MSBUILDDISABLENODEREUSE: "1"
     commands:
       - cd src/backend
       - dotnet restore iLED.slnx
-      - dotnet build iLED.slnx -c Release --no-restore
+      - dotnet build iLED.slnx -c Release --no-restore -m:1
 
   - name: shop
     image: node:22-bookworm
+    environment:
+      NG_BUILD_MAX_WORKERS: "1"
+      NODE_OPTIONS: "--max-old-space-size=1536"
     commands:
       - cd src/shop
       - npm ci
       - npm run build -- --configuration=production
+    depends_on:
+      - api
 
   - name: admin
     image: node:22-bookworm
+    environment:
+      NG_BUILD_MAX_WORKERS: "1"
+      NODE_OPTIONS: "--max-old-space-size=1536"
     commands:
       - cd src/admin
       - npm ci
       - npm run build -- --configuration=production
+    depends_on:
+      - shop
 
 trigger:
   event: