feat: drag-and-drop reorder for daily focus items

Add HTML5 drag-and-drop within domain groups on the focus page.
Items can be dragged to reorder within their domain; cross-domain
drag is prevented. Uses hidden form POST (no fetch/XHR). Arrow
buttons kept as fallback.

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

static/style.css

@@ -1107,6 +1107,11 @@ a:hover { color: var(--accent-hover); }
     transition: width 0.3s;
 }
 
+/* ---- Focus Drag-and-Drop ---- */
+.focus-drag-row { cursor: grab; }
+.focus-drag-row.dragging { opacity: 0.4; background: var(--accent-soft); }
+.focus-drag-row.drag-over { box-shadow: 0 -2px 0 0 var(--accent) inset; }
+
 /* ---- Reorder Grip Handle ---- */
 .reorder-grip {
     display: inline-flex;