feat(tickets): suppression d'un ticket (backend + frontend)

Ajoute la suppression complète d'un ticket (#6).

Backend Rust :
- port IssueStore::delete (NotFound si absent) + event IssueDeleted{freed_sprint}
- FsIssueStore::delete : supprime .ideai/tickets/<N>/ et l'index sous lock
- use case DeleteIssue + adaptations des tests sprint/ticket_assistant au port
- commande Tauri ticket_delete + câblage events/state/lib

Frontend :
- gateway delete (ports, adapter ticket + mock, domain)
- useTicketDetail : retrait de la liste et fermeture du détail via event issueDeleted
- intégration TicketDetail + tests

Tests verts : application/issue_usecases (6), infrastructure/issue_store (7),
app-tauri --lib (56), frontend vitest (503), npm run build (exit 0).

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

crates/app-tauri/src/events.rs

@@ -241,6 +241,16 @@ pub enum DomainEventDto {
         /// New optimistic version.
         version: u64,
     },
+    /// An issue-backed public ticket was deleted.
+    #[serde(rename_all = "camelCase")]
+    IssueDeleted {
+        /// Project id.
+        project_id: String,
+        /// Deleted public ticket reference (`#N`).
+        issue_ref: String,
+        /// Released sprint id, when any.
+        freed_sprint: Option<String>,
+    },
     /// A public ticket status changed.
     #[serde(rename_all = "camelCase")]
     IssueStatusChanged {
@@ -781,6 +791,15 @@ impl From<&DomainEvent> for DomainEventDto {
                 issue_ref: issue_ref.to_string(),
                 version: version.get(),
             },
+            DomainEvent::IssueDeleted {
+                project_id,
+                issue_ref,
+                freed_sprint,
+            } => Self::IssueDeleted {
+                project_id: project_id.to_string(),
+                issue_ref: issue_ref.to_string(),
+                freed_sprint: freed_sprint.map(|sprint| sprint.to_string()),
+            },
             DomainEvent::IssueStatusChanged {
                 issue_ref,
                 status,
@@ -1106,6 +1125,22 @@ mod tests {
         assert_eq!(json["version"], 3);
     }
 
+    #[test]
+    fn issue_deleted_relays_to_dto_and_wire() {
+        let project_id = domain::ProjectId::from_uuid(uuid::Uuid::from_u128(40));
+        let sprint_id = domain::SprintId::from_uuid(uuid::Uuid::from_u128(42));
+        let dto = DomainEventDto::from(&DomainEvent::IssueDeleted {
+            project_id,
+            issue_ref: domain::IssueRef::from(domain::IssueNumber::new(7).unwrap()),
+            freed_sprint: Some(sprint_id),
+        });
+        let json = serde_json::to_value(&dto).expect("serialisable");
+        assert_eq!(json["type"], "issueDeleted");
+        assert_eq!(json["projectId"], project_id.to_string());
+        assert_eq!(json["issueRef"], "#7");
+        assert_eq!(json["freedSprint"], sprint_id.to_string());
+    }
+
     #[test]
     fn ticket_assistant_events_relay_to_dto_and_wire() {
         let profile_id = domain::ProfileId::from_uuid(uuid::Uuid::from_u128(9));