feat: add Docker build cache preservation toggles and development logging

Add two new application settings to control Docker build cache invalidation:
- inject_build_args_to_dockerfile (default: true) - Skip Dockerfile ARG injection
- include_source_commit_in_build (default: false) - Exclude SOURCE_COMMIT from build context

These toggles let users preserve Docker cache when SOURCE_COMMIT or custom ARGs change frequently. Development-only logging shows which ARGs are being injected for debugging.

🤖 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>

app/Models/ApplicationSetting.php

@@ -15,6 +15,8 @@ class ApplicationSetting extends Model
         'is_container_label_escape_enabled' => 'boolean',
         'is_container_label_readonly_enabled' => 'boolean',
         'use_build_secrets' => 'boolean',
+        'inject_build_args_to_dockerfile' => 'boolean',
+        'include_source_commit_in_build' => 'boolean',
         'is_auto_deploy_enabled' => 'boolean',
         'is_force_https_enabled' => 'boolean',
         'is_debug_enabled' => 'boolean',