feat(workspace): make hoisted bullet point header editable in zoom mode

frontend/src/features/workspace/WorkspaceView.tsx

@@ -1391,13 +1391,26 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
                   </div>
                 )}
 
-                {/* If zoomed, show zoomed block as prominent header */}
+                {/* If zoomed, show zoomed block as editable prominent header */}
                 {zoomedBlock && (
-                  <div className="pb-2 border-b border-border">
-                    <h2 className="text-xl font-bold text-main flex items-center gap-2">
-                      <span className="w-2.5 h-2.5 rounded-pill bg-accent" />
-                      <span>{zoomedBlock.content || 'Unbenannter Ast'}</span>
-                    </h2>
+                  <div className="pb-2 border-b border-border flex items-center gap-2.5">
+                    <span className="w-2.5 h-2.5 rounded-pill bg-accent flex-shrink-0" />
+                    <input
+                      type="text"
+                      value={zoomedBlock.content}
+                      onChange={(e) => updateBlock(zoomedBlock.id, { content: e.target.value })}
+                      onKeyDown={(e) => {
+                        if (e.key === 'Enter') {
+                          e.preventDefault();
+                          const zoomIdx = selectedDoc.blocks.findIndex((b) => b.id === zoomedBlock.id);
+                          if (zoomIdx !== -1) {
+                            insertNewBulletAfter(zoomIdx, (zoomedBlock.level || 0) + 1);
+                          }
+                        }
+                      }}
+                      placeholder="Bullet-Titel bearbeiten… (Enter für Unterpunkt)"
+                      className="w-full bg-transparent text-xl font-bold text-main focus:outline-none placeholder:text-faint"
+                    />
                   </div>
                 )}
 
@@ -1683,11 +1696,26 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
                   <button
                     type="button"
                     onClick={() => {
-                      const lastBlock = selectedDoc.blocks[selectedDoc.blocks.length - 1];
-                      insertNewBulletAfter(
-                        selectedDoc.blocks.length - 1,
-                        lastBlock?.level || 0
-                      );
+                      if (zoomedBlock) {
+                        const lastDescendant = visibleBlocks[visibleBlocks.length - 1];
+                        if (lastDescendant) {
+                          insertNewBulletAfter(
+                            lastDescendant.originalIndex,
+                            lastDescendant.block.level || (zoomedBlock.level || 0) + 1
+                          );
+                        } else {
+                          const zoomIdx = selectedDoc.blocks.findIndex((b) => b.id === zoomedBlock.id);
+                          if (zoomIdx !== -1) {
+                            insertNewBulletAfter(zoomIdx, (zoomedBlock.level || 0) + 1);
+                          }
+                        }
+                      } else {
+                        const lastBlock = selectedDoc.blocks[selectedDoc.blocks.length - 1];
+                        insertNewBulletAfter(
+                          selectedDoc.blocks.length - 1,
+                          lastBlock?.level || 0
+                        );
+                      }
                     }}
                     className="btn-action text-xs flex items-center gap-1.5"
                   >