feat(plan): add hard-delete for categories (blocked when in use)

DELETE /plan/categories/:id now hard-deletes the row, guarded: refuses when any live entry/override uses the key (suggests hide instead) and keeps >=1 active category. Modal gains a per-row Smazat with inline confirm. Hiding stays via PATCH is_active.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/components/PlanCategoriesModal.tsx

@@ -20,6 +20,8 @@ export default function PlanCategoriesModal({
   const alert = useAlert();
   const [newLabel, setNewLabel] = useState("");
   const [newColor, setNewColor] = useState(DEFAULT_NEW_COLOR);
+  // Id of the row showing the inline "really delete?" confirm, or null.
+  const [confirmDeleteId, setConfirmDeleteId] = useState<number | null>(null);
 
   const createCat = useApiMutation<
     { label: string; color: string },
@@ -37,6 +39,11 @@ export default function PlanCategoriesModal({
     method: "PATCH",
     invalidate: ["plan", "dashboard", "audit-log"],
   });
+  const deleteCat = useApiMutation<{ id: number }, { ok: true }>({
+    url: (v) => `/api/admin/plan/categories/${v.id}`,
+    method: "DELETE",
+    invalidate: ["plan", "dashboard", "audit-log"],
+  });
 
   const handleAdd = () => {
     const label = newLabel.trim();
@@ -66,7 +73,23 @@ export default function PlanCategoriesModal({
     );
   };
 
-  const busy = createCat.isPending || updateCat.isPending;
+  const handleDelete = (id: number) => {
+    deleteCat.mutate(
+      { id },
+      {
+        onSuccess: () => setConfirmDeleteId(null),
+        // Server blocks deleting a category that is still in use (409) — show
+        // the Czech message ("…můžete ji skrýt") and keep the row.
+        onError: (e) => {
+          alert.error(e.message);
+          setConfirmDeleteId(null);
+        },
+      },
+    );
+  };
+
+  const busy =
+    createCat.isPending || updateCat.isPending || deleteCat.isPending;
 
   return (
     <FormModal
@@ -110,14 +133,47 @@ export default function PlanCategoriesModal({
               }}
               aria-label={`Název – ${c.label}`}
             />
-            <button
-              type="button"
-              className="admin-btn admin-btn-secondary admin-btn-sm"
-              disabled={busy}
-              onClick={() => patch(c.id, { is_active: !c.is_active })}
-            >
-              {c.is_active ? "Skrýt" : "Obnovit"}
-            </button>
+            {confirmDeleteId === c.id ? (
+              <>
+                <button
+                  type="button"
+                  className="admin-btn admin-btn-danger admin-btn-sm"
+                  disabled={busy}
+                  onClick={() => handleDelete(c.id)}
+                >
+                  Opravdu smazat
+                </button>
+                <button
+                  type="button"
+                  className="admin-btn admin-btn-secondary admin-btn-sm"
+                  disabled={busy}
+                  onClick={() => setConfirmDeleteId(null)}
+                >
+                  Zrušit
+                </button>
+              </>
+            ) : (
+              <>
+                <button
+                  type="button"
+                  className="admin-btn admin-btn-secondary admin-btn-sm"
+                  disabled={busy}
+                  onClick={() => patch(c.id, { is_active: !c.is_active })}
+                >
+                  {c.is_active ? "Skrýt" : "Obnovit"}
+                </button>
+                <button
+                  type="button"
+                  className="admin-btn admin-btn-danger admin-btn-sm plan-cat-delete"
+                  disabled={busy}
+                  onClick={() => setConfirmDeleteId(c.id)}
+                  aria-label={`Smazat – ${c.label}`}
+                  title="Smazat kategorii"
+                >
+                  Smazat
+                </button>
+              </>
+            )}
           </div>
         ))}
 

src/admin/plan.css

@@ -1011,3 +1011,13 @@
   padding-top: 10px;
   border-top: 1px dashed var(--plan-paper-rule);
 }
+/* The per-row delete trigger reads quieter than the solid danger confirm
+   button it turns into; keep it an outline until the user commits. */
+.plan-cat-delete.admin-btn-danger {
+  background: transparent;
+  color: #dc2626;
+  border: 1px solid color-mix(in srgb, #dc2626 40%, transparent);
+}
+.plan-cat-delete.admin-btn-danger:hover:not(:disabled) {
+  background: color-mix(in srgb, #dc2626 12%, transparent);
+}