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/application/tests/issue_usecases.rs

@@ -13,7 +13,9 @@ use domain::{
 };
 use uuid::Uuid;
 
-use application::{CreateIssue, CreateIssueInput, UpdateIssue, UpdateIssueInput};
+use application::{
+    CreateIssue, CreateIssueInput, DeleteIssue, DeleteIssueInput, UpdateIssue, UpdateIssueInput,
+};
 
 #[derive(Default)]
 struct FakeIssues {
@@ -84,6 +86,19 @@ impl IssueStore for FakeIssues {
         Ok(())
     }
 
+    async fn delete(
+        &self,
+        _root: &ProjectPath,
+        issue_ref: IssueRef,
+    ) -> Result<(), IssueStoreError> {
+        self.issues
+            .lock()
+            .unwrap()
+            .remove(&issue_ref)
+            .map(|_| ())
+            .ok_or(IssueStoreError::NotFound)
+    }
+
     async fn read_carnet(
         &self,
         _root: &ProjectPath,
@@ -400,3 +415,92 @@ async fn update_issue_maps_version_conflict() {
     assert_eq!(err.code(), "INVALID");
     assert!(err.to_string().contains("version conflict"));
 }
+
+#[tokio::test]
+async fn delete_issue_emits_deleted_event_with_freed_sprint() {
+    let issues = Arc::new(FakeIssues::default());
+    let sprint_id = domain::SprintId::from_uuid(Uuid::from_u128(7));
+    let initial = Issue::new(
+        domain::IssueId::new_random(),
+        IssueNumber::new(1).unwrap(),
+        "In sprint",
+        MarkdownDoc::new("Body"),
+        IssueStatus::Open,
+        IssuePriority::Medium,
+        MarkdownDoc::default(),
+        Vec::new(),
+        Vec::new(),
+        IssueActor::User,
+        1,
+    )
+    .unwrap()
+    .mutate(IssueActor::System, 2, |issue| {
+        issue.sprint = Some(sprint_id);
+    })
+    .unwrap();
+    issues.create(&project().root, &initial).await.unwrap();
+    let bus = Arc::new(SpyBus::default());
+    let uc = DeleteIssue::new(issues.clone(), bus.clone());
+
+    let out = uc
+        .execute(DeleteIssueInput {
+            project: project(),
+            issue_ref: initial.reference(),
+        })
+        .await
+        .unwrap();
+
+    assert_eq!(out.issue_ref, initial.reference());
+    assert!(matches!(
+        issues
+            .get_by_ref(&project().root, initial.reference())
+            .await,
+        Err(IssueStoreError::NotFound)
+    ));
+    assert!(matches!(
+        bus.events().as_slice(),
+        [DomainEvent::IssueDeleted {
+            issue_ref,
+            freed_sprint: Some(id),
+            ..
+        }] if *issue_ref == initial.reference() && *id == sprint_id
+    ));
+}
+
+#[tokio::test]
+async fn delete_issue_emits_deleted_event_without_freed_sprint() {
+    let issues = Arc::new(FakeIssues::default());
+    let initial = Issue::new(
+        domain::IssueId::new_random(),
+        IssueNumber::new(2).unwrap(),
+        "Backlog",
+        MarkdownDoc::new("Body"),
+        IssueStatus::Open,
+        IssuePriority::Medium,
+        MarkdownDoc::default(),
+        Vec::new(),
+        Vec::new(),
+        IssueActor::User,
+        1,
+    )
+    .unwrap();
+    issues.create(&project().root, &initial).await.unwrap();
+    let bus = Arc::new(SpyBus::default());
+    let uc = DeleteIssue::new(issues, bus.clone());
+
+    uc.execute(DeleteIssueInput {
+        project: project(),
+        issue_ref: initial.reference(),
+    })
+    .await
+    .unwrap();
+
+    assert!(matches!(
+        bus.events().as_slice(),
+        [DomainEvent::IssueDeleted {
+            issue_ref,
+            freed_sprint: None,
+            ..
+        }] if *issue_ref == initial.reference()
+    ));
+}