Initial scaffold: Flask webui + APScheduler + Playwright automation for MassPrice rule scheduling

Drives massprice.tcgplayer.com's Run Rule action per-rule on a
user-configured schedule (multiple times/day, day-of-week toggles),
replacing MassPrice's native scheduler (capped at 15 schedules
account-wide, one run/day, with observed clock drift). Deployed via
Forgejo push-to-deploy on Unraid, matching arr-summary/card-grader.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H6TgffxTvYhqxykAbVQg2v

templates/_shell.html

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+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <title>{% block title %}MassPrice Scheduler{% endblock %}</title>
+  <link rel="stylesheet" href="{{ url_for('static', filename='css/style.css') }}">
+</head>
+<body>
+  <header class="topbar">
+    <div class="brand">MassPrice <span>Scheduler</span></div>
+    {% if session.get('authenticated') %}
+    <nav>
+      <a href="{{ url_for('dashboard') }}" class="{{ 'active' if request.endpoint == 'dashboard' else '' }}">Dashboard</a>
+      <a href="{{ url_for('activity') }}" class="{{ 'active' if request.endpoint == 'activity' else '' }}">Activity</a>
+      <a href="{{ url_for('logout') }}">Log Out</a>
+    </nav>
+    {% endif %}
+  </header>
+  <main>
+    {% block content %}{% endblock %}
+  </main>
+  <footer>v{{ app_version }} &middot; {{ app_version_date }}</footer>
+  {% block scripts %}{% endblock %}
+</body>
+</html>