Implement build caching to accelerate compilation

- Add --build-cache-path flag to arduino-cli compile command.
- Create /tmp/arduino-cache directory to store pre-compiled core objects.
- Reduces total CI runtime by reusing compiled RP2040 core files across multiple examples.

Author: jit89

.github/workflows/compile-test.yml

@@ -30,11 +30,17 @@ jobs:
 
       - name: Compile Examples
         run: |
-          - name: Compile Examples
-        run: |
-          # Find every .ino file, get its directory (dirname), and compile that directory
+         # Create the cache directory
+         mkdir -p /tmp/arduino-cache
+          
+          # Find every .ino file, get its directory, and compile with caching
           for example in $(find ./examples -name "*.ino"); do
             EXAMPLE_DIR=$(dirname "$example")
             echo "Compiling sketch in $EXAMPLE_DIR..."
-            $HOME/bin/arduino-cli compile --fqbn rp2040:rp2040:rpipico "$EXAMPLE_DIR"
+            
+            $HOME/bin/arduino-cli compile \
+              --fqbn rp2040:rp2040:rpipico \
+              --build-cache-path /tmp/arduino-cache \
+              "$EXAMPLE_DIR"
           done
+