add pattern analysis feature with web dashboard and CLI

New /patterns page with 9 analyses: chair win bias, bet rank
correlations, hand type distributions, pot size buckets, streaks,
hourly patterns, and recent-vs-overall comparison. Also adds a
standalone analyze.py CLI script for terminal output.

static/analytics.html

@@ -212,7 +212,10 @@
 
 <div class="header">
   <h1>Teen Patti Analytics</h1>
-  <a href="/" class="nav-link">Live Dashboard &rarr;</a>
+  <div style="display:flex;gap:14px">
+    <a href="/" class="nav-link">Live Dashboard &rarr;</a>
+    <a href="/patterns" class="nav-link">Patterns &rarr;</a>
+  </div>
 </div>
 
 <div class="period-bar">