feat(tickets): attribution d'un sprint à la création via popup SprintPicker (#38)

Nouveau composant SprintPicker permettant de choisir un sprint lors de
la création d'un ticket depuis TicketsPanel ; export ajouté à l'index
des features tickets. Frontend-pur.

QA vert : tsc --noEmit exit 0, vitest 63 fichiers / 634 tests passés.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/features/tickets/TicketsPanel.tsx

@@ -14,6 +14,7 @@ import { Button, Input, Panel, Spinner, cn } from "@/shared";
 import { useTickets } from "./useTickets";
 import { useProjectAgents } from "./useProjectAgents";
 import { SprintManager } from "./SprintManager";
+import { SprintPicker } from "./SprintPicker";
 import { TicketFacetsBar } from "./TicketFacetsBar";
 import {
   PriorityBadge,
@@ -42,6 +43,10 @@ export function TicketsPanel({ projectId, onOpen }: TicketsPanelProps) {
   const [showSprints, setShowSprints] = useState(false);
   const [newTitle, setNewTitle] = useState("");
   const [newPriority, setNewPriority] = useState<TicketPriority>("medium");
+  // Sprint chosen for the new ticket (`null` ⇒ "Sans sprint"), and whether its
+  // picker popup is open (#38).
+  const [newSprint, setNewSprint] = useState<Sprint | null>(null);
+  const [showSprintPicker, setShowSprintPicker] = useState(false);
 
   const items = vm.list?.items ?? [];
 
@@ -66,12 +71,18 @@ export function TicketsPanel({ projectId, onOpen }: TicketsPanelProps) {
       title: newTitle.trim(),
       priority: newPriority,
     });
-    if (created) {
-      setNewTitle("");
-      setNewPriority("medium");
-      setShowCreate(false);
-      onOpen(created.ref);
+    if (!created) return; // create failed; `vm.error` already carries the reason.
+    // Two-step assignment (#38): the ticket exists either way. If the sprint
+    // assignment fails, the ticket is kept and `vm.assignSprint` surfaces the
+    // failure via `vm.error` — we never lose the created ticket.
+    if (newSprint) {
+      await vm.assignSprint(created.ref, newSprint.id);
     }
+    setNewTitle("");
+    setNewPriority("medium");
+    setNewSprint(null);
+    setShowCreate(false);
+    onOpen(created.ref);
   }
 
   return (
@@ -146,6 +157,22 @@ export function TicketsPanel({ projectId, onOpen }: TicketsPanelProps) {
               Create
             </Button>
           </div>
+          {/* Sprint field (#38): opens the SprintPicker popup; shows the choice
+              (or "Sans sprint"). */}
+          <div className="flex items-center gap-2">
+            <span className="text-xs text-muted">Sprint</span>
+            <Button
+              type="button"
+              size="sm"
+              variant="ghost"
+              aria-label="choose sprint for new ticket"
+              disabled={vm.busy}
+              onClick={() => setShowSprintPicker(true)}
+              className="border border-border"
+            >
+              {newSprint ? newSprint.name : "Sans sprint"}
+            </Button>
+          </div>
         </form>
       )}
 
@@ -252,6 +279,17 @@ export function TicketsPanel({ projectId, onOpen }: TicketsPanelProps) {
           onClose={() => setShowSprints(false)}
         />
       )}
+
+      {/* Sprint picker for the create form (#38) — chrome-level, nested z-index,
+          focus-trapped. Selecting an entry sets the pending sprint and closes. */}
+      <SprintPicker
+        open={showSprintPicker}
+        projectId={projectId}
+        selectedSprintId={newSprint?.id ?? null}
+        title="Sprint du nouveau ticket"
+        onSelect={(sprint) => setNewSprint(sprint)}
+        onClose={() => setShowSprintPicker(false)}
+      />
     </Panel>
   );
 }