feat:實作 Member Portal MVP 前端與後端整合

後端：
- 新增 DivingOffer Model / DivingOfferController（列表+詳情 API，支援搜尋/篩選/分頁）
- 修正 Google OAuth callback 改為 redirect 至前端（SocialAuthController）
- 新增 config/cors.php 允許前端 origin
- .gitignore 新增 frontend/ 排除規則

前端（frontend/）：
- Vue 3 + Vite + Tailwind CSS + Pinia + Vue Router
- 頁面：首頁、課程列表、課程詳情、登入、註冊、個人資料、OAuth callback
- 整合至 Docker（multi-stage build，nginx 靜態服務於 port 5173）

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

frontend/src/components/HelloWorld.vue

@@ -0,0 +1,95 @@
+<script setup>
+import { ref } from 'vue'
+import viteLogo from '../assets/vite.svg'
+import heroImg from '../assets/hero.png'
+import vueLogo from '../assets/vue.svg'
+
+const count = ref(0)
+</script>
+
+<template>
+  <section id="center">
+    <div class="hero">
+      <img :src="heroImg" class="base" width="170" height="179" alt="" />
+      <img :src="vueLogo" class="framework" alt="Vue logo" />
+      <img :src="viteLogo" class="vite" alt="Vite logo" />
+    </div>
+    <div>
+      <h1>Get started</h1>
+      <p>Edit <code>src/App.vue</code> and save to test <code>HMR</code></p>
+    </div>
+    <button type="button" class="counter" @click="count++">
+      Count is {{ count }}
+    </button>
+  </section>
+
+  <div class="ticks"></div>
+
+  <section id="next-steps">
+    <div id="docs">
+      <svg class="icon" role="presentation" aria-hidden="true">
+        <use href="/icons.svg#documentation-icon"></use>
+      </svg>
+      <h2>Documentation</h2>
+      <p>Your questions, answered</p>
+      <ul>
+        <li>
+          <a href="https://vite.dev/" target="_blank">
+            <img class="logo" :src="viteLogo" alt="" />
+            Explore Vite
+          </a>
+        </li>
+        <li>
+          <a href="https://vuejs.org/" target="_blank">
+            <img class="button-icon" :src="vueLogo" alt="" />
+            Learn more
+          </a>
+        </li>
+      </ul>
+    </div>
+    <div id="social">
+      <svg class="icon" role="presentation" aria-hidden="true">
+        <use href="/icons.svg#social-icon"></use>
+      </svg>
+      <h2>Connect with us</h2>
+      <p>Join the Vite community</p>
+      <ul>
+        <li>
+          <a href="https://github.com/vitejs/vite" target="_blank">
+            <svg class="button-icon" role="presentation" aria-hidden="true">
+              <use href="/icons.svg#github-icon"></use>
+            </svg>
+            GitHub
+          </a>
+        </li>
+        <li>
+          <a href="https://chat.vite.dev/" target="_blank">
+            <svg class="button-icon" role="presentation" aria-hidden="true">
+              <use href="/icons.svg#discord-icon"></use>
+            </svg>
+            Discord
+          </a>
+        </li>
+        <li>
+          <a href="https://x.com/vite_js" target="_blank">
+            <svg class="button-icon" role="presentation" aria-hidden="true">
+              <use href="/icons.svg#x-icon"></use>
+            </svg>
+            X.com
+          </a>
+        </li>
+        <li>
+          <a href="https://bsky.app/profile/vite.dev" target="_blank">
+            <svg class="button-icon" role="presentation" aria-hidden="true">
+              <use href="/icons.svg#bluesky-icon"></use>
+            </svg>
+            Bluesky
+          </a>
+        </li>
+      </ul>
+    </div>
+  </section>
+
+  <div class="ticks"></div>
+  <section id="spacer"></section>
+</template>