feat: 即時預約聊天室（realtime booking chat）

## 新增功能
- 會員與教練在 confirmed 預約期間可互傳文字與圖片訊息
- Presence Channel 顯示對方在線狀態（即時加入/離線）
- 已讀回執：對方讀取訊息後即時更新
- 預約完成（completed）後訊息封存唯讀
- 圖片上傳使用 intervention/image 處理（移除 EXIF、限制尺寸、強制重新編碼）

## 通知系統
- 收到新訊息時 Bell Icon 即時更新（NotificationCreated via private channel）
- 預約列表卡片顯示未讀角標（GET /api/bookings/messages/unread-counts 批次查詢）
- 瀏覽器分頁在背景時推送 Web Notification

## 基礎建設
- 引入 Laravel Reverb 作為自架 WebSocket 伺服器
- docker-compose 新增 reverb service（連接 proxy_net，供 NPM 代理）
- 前端安裝 laravel-echo + pusher-js，初始化 Echo plugin
- Dockerfile 補 GD JPEG/WebP/FreeType 支援

## 清理
- 移除 test_broadcast.php 與 resources/js/echo.js（Blade 殘留）
- 移除 /ping、/testpost 測試路由
- channels.php 改用 class-based 授權語法，移除 debug log
- BookingChat.vue otherType 提取為 computed 消除重複
- docker-entrypoint.sh 健康檢查改用 env var 取代硬編碼密碼

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

config/broadcasting.php

@@ -0,0 +1,82 @@
+<?php
+
+return [
+
+    /*
+    |--------------------------------------------------------------------------
+    | Default Broadcaster
+    |--------------------------------------------------------------------------
+    |
+    | This option controls the default broadcaster that will be used by the
+    | framework when an event needs to be broadcast. You may set this to
+    | any of the connections defined in the "connections" array below.
+    |
+    | Supported: "reverb", "pusher", "ably", "redis", "log", "null"
+    |
+    */
+
+    'default' => env('BROADCAST_CONNECTION', 'null'),
+
+    /*
+    |--------------------------------------------------------------------------
+    | Broadcast Connections
+    |--------------------------------------------------------------------------
+    |
+    | Here you may define all of the broadcast connections that will be used
+    | to broadcast events to other systems or over WebSockets. Samples of
+    | each available type of connection are provided inside this array.
+    |
+    */
+
+    'connections' => [
+
+        'reverb' => [
+            'driver' => 'reverb',
+            'key' => env('REVERB_APP_KEY'),
+            'secret' => env('REVERB_APP_SECRET'),
+            'app_id' => env('REVERB_APP_ID'),
+            'options' => [
+                'host' => env('REVERB_HOST'),
+                'port' => env('REVERB_PORT', 443),
+                'scheme' => env('REVERB_SCHEME', 'https'),
+                'useTLS' => env('REVERB_SCHEME', 'https') === 'https',
+            ],
+            'client_options' => [
+                // Guzzle client options: https://docs.guzzlephp.org/en/stable/request-options.html
+            ],
+        ],
+
+        'pusher' => [
+            'driver' => 'pusher',
+            'key' => env('PUSHER_APP_KEY'),
+            'secret' => env('PUSHER_APP_SECRET'),
+            'app_id' => env('PUSHER_APP_ID'),
+            'options' => [
+                'cluster' => env('PUSHER_APP_CLUSTER'),
+                'host' => env('PUSHER_HOST') ?: 'api-'.env('PUSHER_APP_CLUSTER', 'mt1').'.pusher.com',
+                'port' => env('PUSHER_PORT', 443),
+                'scheme' => env('PUSHER_SCHEME', 'https'),
+                'encrypted' => true,
+                'useTLS' => env('PUSHER_SCHEME', 'https') === 'https',
+            ],
+            'client_options' => [
+                // Guzzle client options: https://docs.guzzlephp.org/en/stable/request-options.html
+            ],
+        ],
+
+        'ably' => [
+            'driver' => 'ably',
+            'key' => env('ABLY_KEY'),
+        ],
+
+        'log' => [
+            'driver' => 'log',
+        ],
+
+        'null' => [
+            'driver' => 'null',
+        ],
+
+    ],
+
+];

config/reverb.php

@@ -0,0 +1,102 @@
+<?php
+
+return [
+
+    /*
+    |--------------------------------------------------------------------------
+    | Default Reverb Server
+    |--------------------------------------------------------------------------
+    |
+    | This option controls the default server used by Reverb to handle
+    | incoming messages as well as broadcasting message to all your
+    | connected clients. At this time only "reverb" is supported.
+    |
+    */
+
+    'default' => env('REVERB_SERVER', 'reverb'),
+
+    /*
+    |--------------------------------------------------------------------------
+    | Reverb Servers
+    |--------------------------------------------------------------------------
+    |
+    | Here you may define details for each of the supported Reverb servers.
+    | Each server has its own configuration options that are defined in
+    | the array below. You should ensure all the options are present.
+    |
+    */
+
+    'servers' => [
+
+        'reverb' => [
+            'host' => env('REVERB_SERVER_HOST', '0.0.0.0'),
+            'port' => env('REVERB_SERVER_PORT', 8080),
+            'path' => env('REVERB_SERVER_PATH', ''),
+            'hostname' => env('REVERB_SERVER_HOSTNAME', null),
+            'options' => [
+                'tls' => [],
+            ],
+            'max_request_size' => env('REVERB_MAX_REQUEST_SIZE', 10_000),
+            'scaling' => [
+                'enabled' => env('REVERB_SCALING_ENABLED', false),
+                'channel' => env('REVERB_SCALING_CHANNEL', 'reverb'),
+                'server' => [
+                    'url' => env('REDIS_URL'),
+                    'host' => env('REDIS_HOST', '127.0.0.1'),
+                    'port' => env('REDIS_PORT', '6379'),
+                    'username' => env('REDIS_USERNAME'),
+                    'password' => env('REDIS_PASSWORD'),
+                    'database' => env('REDIS_DB', '0'),
+                    'timeout' => env('REDIS_TIMEOUT', 60),
+                ],
+            ],
+            'pulse_ingest_interval' => env('REVERB_PULSE_INGEST_INTERVAL', 15),
+            'telescope_ingest_interval' => env('REVERB_TELESCOPE_INGEST_INTERVAL', 15),
+        ],
+
+    ],
+
+    /*
+    |--------------------------------------------------------------------------
+    | Reverb Applications
+    |--------------------------------------------------------------------------
+    |
+    | Here you may define how Reverb applications are managed. If you choose
+    | to use the "config" provider, you may define an array of apps which
+    | your server will support, including their connection credentials.
+    |
+    */
+
+    'apps' => [
+
+        'provider' => 'config',
+
+        'apps' => [
+            [
+                'key' => env('REVERB_APP_KEY'),
+                'secret' => env('REVERB_APP_SECRET'),
+                'app_id' => env('REVERB_APP_ID'),
+                'options' => [
+                    'host' => env('REVERB_HOST'),
+                    'port' => env('REVERB_PORT', 443),
+                    'scheme' => env('REVERB_SCHEME', 'https'),
+                    'useTLS' => env('REVERB_SCHEME', 'https') === 'https',
+                ],
+                'allowed_origins' => ['*'],
+                'ping_interval' => env('REVERB_APP_PING_INTERVAL', 60),
+                'activity_timeout' => env('REVERB_APP_ACTIVITY_TIMEOUT', 30),
+                'max_connections' => env('REVERB_APP_MAX_CONNECTIONS'),
+                'max_message_size' => env('REVERB_APP_MAX_MESSAGE_SIZE', 10_000),
+                'accept_client_events_from' => env('REVERB_APP_ACCEPT_CLIENT_EVENTS_FROM', 'members'),
+                'rate_limiting' => [
+                    'enabled' => env('REVERB_APP_RATE_LIMITING_ENABLED', false),
+                    'max_attempts' => env('REVERB_APP_RATE_LIMIT_MAX_ATTEMPTS', 60),
+                    'decay_seconds' => env('REVERB_APP_RATE_LIMIT_DECAY_SECONDS', 60),
+                    'terminate_on_limit' => env('REVERB_APP_RATE_LIMIT_TERMINATE', false),
+                ],
+            ],
+        ],
+
+    ],
+
+];