feat: add claudeArgs input for direct CLI argument passing

- Add claude_args input to both action.yml files
- Implement shell-style argument parsing with quote handling
- Pass arguments directly to Claude CLI for maximum flexibility
- Add comprehensive tests for argument parsing
- Log custom arguments for debugging

Users can now pass any Claude CLI arguments directly:
  claude_args: '--max-turns 3 --mcp-config /path/to/config.json'

This provides power users full control over Claude's behavior without
waiting for specific inputs to be added to the action.

action.yml

@@ -89,6 +89,10 @@ inputs:
     description: "Timeout in minutes for execution"
     required: false
     default: "30"
+  claude_args:
+    description: "Additional arguments to pass directly to Claude CLI"
+    required: false
+    default: ""
   use_sticky_comment:
     description: "Use just one comment to deliver issue/PR comments"
     required: false
@@ -193,6 +197,7 @@ runs:
         INPUT_TIMEOUT_MINUTES: ${{ inputs.timeout_minutes }}
         INPUT_CLAUDE_ENV: ${{ inputs.claude_env }}
         INPUT_FALLBACK_MODEL: ${{ inputs.fallback_model }}
+        INPUT_CLAUDE_ARGS: ${{ inputs.claude_args }}
         INPUT_EXPERIMENTAL_SLASH_COMMANDS_DIR: ${{ github.action_path }}/slash-commands
 
         # Model configuration