docs: clarify VM execution tests are Linux-only (Firecracker requirement)

Firecracker is a Linux-specific hypervisor and will not work on macOS/Windows.

Added platform clarification to workflow header to document that:
- VM execution tests require Linux
- On macOS/Windows, these would only work inside a Linux VM
- The experimental fcctl-web code is gitignored
- Tests skip gracefully when experimental code is not present

Author: Terraphim AI

.github/workflows/vm-execution-tests.yml

@@ -1,5 +1,10 @@
 name: VM Execution Tests
 
+# NOTE: This workflow tests experimental VM execution features using Firecracker
+# Firecracker is Linux-only - these tests will not work on macOS/Windows
+# The scratchpad/firecracker-rust directory is gitignored (experimental code)
+# Tests will skip gracefully if the directory is not present
+
 on:
   push:
     branches: [ main, develop, agent_system ]
@@ -28,6 +33,11 @@ jobs:
     timeout-minutes: 15
 
     steps:
+    - name: Platform check
+      run: |
+        echo "⚠️ VM execution tests are Linux-only (Firecracker requirement)"
+        echo "Running on: ubuntu-latest ✅"
+    
     - name: Checkout code
       uses: actions/checkout@v4