fix: Share panel — General Access dropdown + Publish section

Share panel restructured to match Notion:
- General Access: dropdown with 'Only people invited' / 'Anyone with the link'
- Invite: email + permission selector
- Publish to web: toggle + URL input + Copy link button
- Copy page link at bottom

CSS: .share-access-btn and .share-access-menu for the access dropdown

static/css/app.css

@@ -2254,6 +2254,28 @@ input, select, textarea { font-family: inherit; color: inherit; }
 }
 .share-dd-btn:hover { opacity: 0.9; }
 
+/* ── General Access dropdown ── */
+.share-access-btn {
+  width: 100%; display: flex; align-items: center; justify-content: space-between;
+  padding: 8px 12px; background: var(--bg-primary);
+  border: 1px solid var(--border); border-radius: 6px;
+  color: var(--text-primary); font-size: 13px; cursor: pointer;
+  margin-top: 4px;
+}
+.share-access-btn:hover { background: var(--bg-hover); }
+.share-access-btn .chevron-down { font-size: 10px; opacity: 0.5; }
+.share-access-menu {
+  position: absolute; top: 100%; left: 0; right: 0; margin-top: 2px;
+  background: var(--bg-primary); border: 1px solid var(--border);
+  border-radius: 6px; box-shadow: 0 4px 12px rgba(0,0,0,0.3);
+  z-index: 210; padding: 4px 0;
+}
+.share-access-option {
+  padding: 8px 14px; font-size: 13px; color: var(--text-primary);
+  cursor: pointer; display: flex; align-items: center; gap: 8px;
+}
+.share-access-option:hover { background: var(--bg-hover); }
+
 /* ── More menu dropdown ── */
 .more-menu {
   position: absolute; top: calc(100% + 4px); right: 0;