dashboard: drop "held locally · prices via /api/universe" meta line

Subtitle was technical noise that didn't earn its space in the header.
Title alone reads cleaner. Kept the scoped panel-header layout override
in cassandra.css since it's harmless and future-proof against re-adding
header children.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/templates/dashboard.html

@@ -47,7 +47,6 @@
 <section id="portfolio-panel" class="panel">
   <div class="panel-header">
     <span class="title">Portfolio</span>
-    <span class="meta">held locally · prices via /api/universe</span>
     <button type="button" id="pf-edit-btn" class="pf-edit-btn"
             title="Add or remove positions" aria-pressed="false">
       <svg width="14" height="14" viewBox="0 0 24 24" fill="none"