feat(agent): reprise des sessions au redémarrage (B2) — commande + ResumeProjectPanel

- Tauri : commande list_resumable_agents (projectId) + ResumableAgentListDto
  { resumable } / ResumableAgentDto (camelCase, conversationId omis si None),
  câblage state.rs (réutilise stores + ProfileStore, aucun nouveau port).
- Front : gateway listResumableAgents, ResumeProjectPanel monté à l'ouverture
  de projet (opt-in, FR) : Reprendre (launch_agent nodeId+conversationId),
  Nouvelle conversation (setCellConversation(null) puis launch), Ignorer,
  Tout reprendre/ignorer. resumeSupported=false ⇒ « relance à neuf ».
- doc : §15.2 coquille agents→resumable (alignée use case/back/front).

Tests : app-tauri dto 9/9 ; vitest 324 (+10) ; workspace Rust 0 échec. 0 régression.

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

frontend/src/adapters/mock/index.ts

@@ -29,6 +29,7 @@ import type {
   MemoryType,
   Project,
   ProfileAvailability,
+  ResumableAgent,
   Skill,
   SkillScope,
   Template,
@@ -211,6 +212,21 @@ export class MockAgentGateway implements AgentGateway {
       }));
   }
 
+  /**
+   * Resumable agents per project, seeded by tests via
+   * {@link _setResumableAgents}. Empty by default (no panel on open).
+   */
+  private resumable = new Map<string, ResumableAgent[]>();
+
+  /** Seeds the resumable inventory returned for a project (deterministic tests). */
+  _setResumableAgents(projectId: string, list: ResumableAgent[]): void {
+    this.resumable.set(projectId, list);
+  }
+
+  async listResumableAgents(projectId: string): Promise<ResumableAgent[]> {
+    return structuredClone(this.resumable.get(projectId) ?? []);
+  }
+
   async attachLiveAgent(
     projectId: string,
     agentId: string,