feat:實作預約系統 — 時段管理、預約生命週期與前端整合

後端：
- 新增 course_schedules / bookings migration（含索引）
- BookingStatus / ScheduleStatus PHP BackedEnum
- CourseSchedule / Booking Model（七狀態機 VALID_TRANSITIONS）
- ScheduleController、ProviderBookingController、MemberBookingController
- 雙層名額驗證（API 層快速失敗 + DB lockForUpdate 防超賣）
- 24h 取消截止、pending 不佔位設計
- ExpirePendingBookings（每小時）/ CompleteFinishedBookings（每日）Scheduler
- Docker cron 配置、CACHE_STORE 改為 file 修正 502

前端：
- 課程詳情頁加入時段選擇與預約流程
- 我的預約頁（展開式卡片、狀態說明、連結課程詳情）
- Coach 時段管理（上午/下午時間選擇器、新課程引導）
- Coach 預約管理（依課程分組、待確認徽章）
- Navbar 新增「我的預約」與「時段/預約管理」入口
- 密碼格式提示與即時比對

OpenSpec：
- booking-system change 歸檔至 archive/2026-05-12-booking-system
- 新增 specs/course-scheduling 與 specs/booking-lifecycle 主規格

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

database/migrations/2026_05_11_144005_create_course_schedules_table.php

@@ -0,0 +1,37 @@
+<?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::create('course_schedules', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('diving_offer_id')->constrained('diving_offers')->cascadeOnDelete();
+            $table->foreignId('provider_id')->constrained('users')->cascadeOnDelete();
+            $table->date('scheduled_date');
+            $table->time('start_time');
+            $table->unsignedInteger('max_participants');
+            $table->unsignedInteger('current_participants')->default(0);
+            $table->string('status')->default('open');
+            $table->timestamps();
+
+            $table->index(['diving_offer_id', 'status', 'scheduled_date'], 'idx_offer_status_date');
+            $table->index('provider_id', 'idx_provider_id');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('course_schedules');
+    }
+};

database/migrations/2026_05_11_144028_create_bookings_table.php

@@ -0,0 +1,38 @@
+<?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::create('bookings', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('schedule_id')->constrained('course_schedules')->cascadeOnDelete();
+            $table->foreignId('member_id')->constrained('users')->cascadeOnDelete();
+            $table->unsignedInteger('participants')->default(1);
+            $table->unsignedInteger('total_price');
+            $table->string('status')->default('pending');
+            $table->text('notes')->nullable();
+            $table->timestamps();
+
+            $table->index(['member_id', 'status'], 'idx_member_status');
+            $table->index(['schedule_id', 'status'], 'idx_schedule_status');
+            $table->index(['status', 'created_at'], 'idx_status_created_at');
+            $table->index(['status', 'schedule_id'], 'idx_status_sched');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('bookings');
+    }
+};