Initial commit: habit tracker PWA with Google OAuth, push notifications

FastAPI + SQLAlchemy/Alembic + MariaDB backend with Jinja2/htmx/Alpine
server-rendered frontend. Multi-user via Google OAuth, daily habit
tracking, monthly/weekly history views, Web Push reminders via
APScheduler, and PWA support (manifest, service worker, offline caching).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/templates/partials/today_content.html

@@ -0,0 +1,43 @@
+{% if celebrate_streak %}
+<div class="celebration-banner" x-data="{ show: true }" x-init="setTimeout(() => show = false, 4000)" x-show="show" x-transition>
+  🎉 <strong>{{ celebrate_habit_name }}</strong> {{ celebrate_streak }}일 연속 달성! 축하해요!
+</div>
+{% endif %}
+
+<div
+  class="card"
+  style="display:flex; align-items:center; justify-content:space-between; flex-wrap:wrap; gap:8px;"
+  x-data="{ pushState: 'checking' }"
+  x-init="habitPush.getSubscriptionState().then(s => pushState = s)"
+>
+  <h2 style="margin:0;">오늘</h2>
+  <div style="display:flex; align-items:center; gap:8px;">
+    <span class="badge">{{ checked_count }}/{{ total_count }} 완료</span>
+    <button
+      type="button"
+      class="btn btn-secondary"
+      x-show="pushState === 'unsubscribed'"
+      x-cloak
+      @click="habitPush.subscribePush().then(ok => { if (ok) pushState = 'subscribed'; })"
+    >알림 켜기</button>
+    <span class="badge" x-show="pushState === 'subscribed'" x-cloak>🔔 알림 켜짐</span>
+  </div>
+</div>
+
+<h2>형성 습관</h2>
+<div class="card">
+  {% for item in build_items %}
+    {% include "partials/today_item.html" %}
+  {% else %}
+    <div class="empty-state">오늘 예정된 형성 습관이 없어요.</div>
+  {% endfor %}
+</div>
+
+<h2>중단 습관</h2>
+<div class="card">
+  {% for item in quit_items %}
+    {% include "partials/today_item.html" %}
+  {% else %}
+    <div class="empty-state">오늘 예정된 중단 습관이 없어요.</div>
+  {% endfor %}
+</div>