feat: add base template with Pico CSS dark theme and home page

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/templates/pages/home.html

@@ -0,0 +1,12 @@
+{% extends "base.html" %}
+
+{% block title %}SneakySwole — Home{% endblock %}
+
+{% block content %}
+<hgroup>
+    <h1>SneakySwole</h1>
+    <p>Your open-source workout tracker</p>
+</hgroup>
+
+<p>Welcome to SneakySwole. Get started by logging in.</p>
+{% endblock %}