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_item.html

@@ -0,0 +1,27 @@
+<div class="habit-item{{ ' today-checked' if item.checked }}">
+  <div class="habit-item-main">
+    <button
+      type="button"
+      class="check-indicator{{ ' checked' if item.checked }}"
+      hx-post="/today/{{ item.habit_id }}/toggle"
+      hx-target="#today-content"
+      hx-swap="innerHTML"
+      aria-label="{{ item.name }} 체크"
+    >{% if item.checked %}&#10003;{% endif %}</button>
+    <div>
+      <div class="habit-item-name">{{ item.name }}</div>
+      {% if item.condition_text %}<div class="habit-item-condition">{{ item.condition_text }}</div>{% endif %}
+      {% if item.reminder_time %}<div class="habit-item-meta">알람 {{ item.reminder_time }}</div>{% endif %}
+      {% if item.scheduled_days > 0 %}
+      <div class="habit-item-stats">
+        <span class="badge">완료율 {{ item.completion_rate }}%</span>
+        {% if item.current_streak > 0 %}
+        <span class="badge{{ ' badge-milestone' if is_milestone_streak(item.current_streak) }}">
+          {{ '🏆' if is_milestone_streak(item.current_streak) else '🔥' }} 연속 {{ item.current_streak }}일
+        </span>
+        {% endif %}
+      </div>
+      {% endif %}
+    </div>
+  </div>
+</div>