fix: Resolve host.docker.internal hostname resolution issue

- Change cache host from 'host.docker.internal' to empty string
- Allow act_runner to auto-detect the correct host IP address
- Update all runner configs: docker, heavy, light, security
- Improve troubleshooting scripts with host IP detection:
  - Linux/macOS: Use ip route, hostname -I, or ifconfig
  - Windows: Use Get-NetIPAddress PowerShell cmdlets
- Update documentation to reflect auto-detection approach

This resolves the 'getaddrinfo ENOTFOUND host.docker.internal' error
by using a more compatible approach that works across different
Docker setups and operating systems.

docs/CACHE_TROUBLESHOOTING.md

@@ -32,7 +32,7 @@ This ensures that cache failures don't cause the entire pipeline to fail.
 ### 2. Runner Configuration Fixes
 
 Updated all existing runner configuration files with:
-- **Fixed Host**: `host.docker.internal` (allows containers to access host)
+- **Auto-detect Host**: Empty host field (allows act_runner to auto-detect the correct IP)
 - **Fixed Port**: `44029` (instead of random port 0)
 - **Host Network**: Uses host networking for better connectivity
 
@@ -91,7 +91,7 @@ Update your runner configuration with these key changes:
 ```yaml
 cache:
   enabled: true
-  host: "host.docker.internal"  # Fixed host
+  host: ""                      # Auto-detect host IP
   port: 44029                   # Fixed port
 
 container: