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>

database/migrations/2025_11_26_000000_add_build_cache_settings_to_application_settings.php

@@ -0,0 +1,30 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('application_settings', function (Blueprint $table) {
+            $table->boolean('inject_build_args_to_dockerfile')->default(true)->after('use_build_secrets');
+            $table->boolean('include_source_commit_in_build')->default(false)->after('inject_build_args_to_dockerfile');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('application_settings', function (Blueprint $table) {
+            $table->dropColumn('inject_build_args_to_dockerfile');
+            $table->dropColumn('include_source_commit_in_build');
+        });
+    }
+};