Fix: Use Node.js 16 for node-sass compatibility

- Changed from node:20 to node:16 in both test and build steps
- Node.js 16 LTS is compatible with node-sass and node-gyp
- This fixes the 'gyp ERR! Cannot assign to read only property cflags' error
- Node.js 20's node-gyp has breaking changes incompatible with older node-sass

.drone.yml

@@ -5,7 +5,7 @@ name: default
 steps:
   # Step 1: Install dependencies and run linting
   - name: test
-    image: node:20
+    image: node:16
     commands:
       - npm ci
       - npm run lint || echo "⚠ Linting skipped (no lint script found)"
@@ -15,7 +15,7 @@ steps:
 
   # Step 2: Build for production (to verify it compiles)
   - name: build
-    image: node:20
+    image: node:16
     commands:
       - npm ci
       - npm run build