feat: initial postcard manager - FastAPI + Jinja2 + SQLite

app/templates/login.html

@@ -0,0 +1,18 @@
+{% extends "base.html" %}
+{% block title %}登录 - Postcard Manager{% endblock %}
+{% block content %}
+<div class="auth-form">
+    <h2>登录</h2>
+    {% if error %}
+    <div class="alert alert-error">{{ error }}</div>
+    {% endif %}
+    <form method="post" action="/login">
+        <label>用户名</label>
+        <input type="text" name="username" required autofocus>
+        <label>密码</label>
+        <input type="password" name="password" required>
+        <button type="submit" class="btn btn-primary">登录</button>
+    </form>
+    <p class="auth-link">没有账号？<a href="/register">注册</a></p>
+</div>
+{% endblock %}