feat(database): column resize, context menu, SVG icons, move New Page to bottom

- Column resize: drag handle between headers to resize column width
- SVG outline icons per property type in header (Aa, #, ☰, 📅, ☑, 🔗, ✉, 📞)
- Header context menu on click: Show page icon toggle, AI Autofill, Filter,
  Sort (asc/desc), Group, Calculate (None/Count/Percent), Freeze, Wrap,
  Insert left/right
- Submenus for AI Autofill, Sort, Calculate with nested options
- New Page button moved below last data row (bottom of table)
- New rows inserted at end of table

static/css/app.css

@@ -3858,6 +3858,94 @@ button.breadcrumb-current { max-width: 260px; }
 }
 .db-btn-create:hover { opacity: 0.9; }
 
+/* ── Column Resize Handle ── */
+.db-col-resize-handle {
+  position: absolute;
+  top: 0; right: 0;
+  width: 5px; height: 100%;
+  cursor: col-resize;
+  z-index: 2;
+  transition: background 0.1s;
+}
+.db-col-resize-handle:hover,
+.db-col-resize-handle:active {
+  background: var(--accent, #2383E2);
+}
+
+/* ── Column Header Context Menu ── */
+.db-col-menu {
+  position: fixed;
+  min-width: 240px;
+  max-width: 320px;
+  background: var(--bg-modal);
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  box-shadow: 0 8px 24px rgba(0,0,0,0.14);
+  z-index: 800;
+  padding: 4px 0;
+  font-family: var(--font-sans);
+  font-size: 13px;
+  color: var(--text-primary);
+}
+
+.db-col-menu-header {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 8px 12px;
+  font-weight: 600;
+}
+.db-col-menu-icon { display: flex; align-items: center; color: var(--text-dim); }
+.db-col-menu-name { flex: 1; }
+.db-col-menu-info { font-size: 11px; color: var(--text-dim); }
+
+.db-col-menu-sep {
+  height: 1px;
+  background: var(--border);
+  margin: 4px 0;
+}
+
+.db-col-menu-item {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 6px 12px;
+  cursor: pointer;
+  transition: background 0.1s;
+  position: relative;
+}
+.db-col-menu-item:hover { background: var(--bg-hover); }
+.db-col-menu-item.has-sub { justify-content: space-between; }
+
+.db-col-menu-toggle { font-size: 11px; font-weight: 600; }
+.db-col-menu-toggle.on { color: var(--accent, #2383E2); }
+.db-col-menu-toggle.off { color: var(--text-dim); }
+
+.db-col-menu-hint { font-size: 11px; color: var(--text-dim); margin-left: auto; margin-right: 4px; }
+.db-col-menu-arrow { font-size: 14px; color: var(--text-dim); }
+.db-col-menu-tag {
+  font-size: 10px;
+  background: var(--accent, #2383E2);
+  color: white;
+  padding: 1px 6px;
+  border-radius: 8px;
+  margin-left: auto;
+}
+
+.db-col-menu-sub {
+  border-left: 1px solid var(--border);
+  margin-left: 0;
+}
+.db-col-menu-sub .sub-item { padding-left: 28px; }
+.db-col-menu-sub .sub-item.checked { font-weight: 600; }
+
+.db-col-menu-subnote {
+  padding: 4px 12px 4px 28px;
+  font-size: 11px;
+  color: var(--text-dim);
+  line-height: 1.4;
+}
+
 /* ── Responsive ── */
 @media (max-width: 768px) {
   .database-table-container { padding: 0 16px; }