feat: Board, BoardColumn, Card, User tables

app/database/migrations/2026_10_11_000001_create_users_table.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void {
+        Schema::create('users', function (Blueprint $table): void {
+            $table->increments('user_id');
+            $table->string('email', 255);
+            $table->string('password_hash', 255);
+            $table->string('name', 255);
+            $table->timestamp('created_datetime')->useCurrent();
+            $table->timestamp('updated_datetime')->nullable();
+
+            $table->unique('email', 'idx_email');
+        });
+    }
+
+    public function down(): void {
+        Schema::dropIfExists('users');
+    }
+};

app/database/migrations/2026_10_11_000002_create_boards_table.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void {
+        Schema::create('boards', function (Blueprint $table): void {
+            $table->increments('board_id');
+            $table->string('title', 255);
+            $table->integer('owner_user_id');
+            $table->boolean('is_public')->default(false);
+            $table->timestamp('created_datetime')->useCurrent();
+            $table->timestamp('updated_datetime')->nullable();
+
+            $table->foreign('owner_user_id')
+                ->references('user_id')
+                ->on('users')
+                ->onDelete('cascade');
+        });
+    }
+
+    public function down(): void {
+        Schema::dropIfExists('boards');
+    }
+};

app/database/migrations/2026_10_11_000003_create_board_columns_table.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void {
+        Schema::create('board_columns', function (Blueprint $table): void {
+            $table->increments('column_id');
+            $table->integer('board_id');
+            $table->smallInteger('ordinal_position');
+            $table->string('title', 255);
+            $table->string('color', 6)->nullable();
+
+            $table->index('board_id', 'idx_board_id');
+
+            $table->foreign('board_id')
+                ->references('board_id')
+                ->on('boards')
+                ->onDelete('cascade');
+        });
+    }
+
+    public function down(): void {
+        Schema::dropIfExists('board_columns');
+    }
+};

app/database/migrations/2026_10_11_000004_create_cards_table.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void {
+        Schema::create('cards', function (Blueprint $table): void {
+            $table->increments('card_id');
+            $table->integer('board_id');
+            $table->integer('column_id');
+            $table->smallInteger('sort_index');
+            $table->string('title', 255);
+            $table->text('content')->nullable();
+            $table->string('color', 6)->nullable();
+            $table->boolean('is_archived')->default(false);
+            $table->timestamp('created_datetime')->useCurrent();
+            $table->timestamp('updated_datetime')->nullable();
+
+            $table->foreign('board_id')
+                ->references('board_id')
+                ->on('boards')
+                ->onDelete('cascade');
+
+            $table->foreign('column_id')
+                ->references('column_id')
+                ->on('board_columns')
+                ->onDelete('cascade');
+        });
+
+        DB::statement('create index "idx_active_board_id" on "cards" ("board_id") where "is_archived" = false');
+    }
+
+    public function down(): void {
+        Schema::dropIfExists('cards');
+    }
+};