feat(session-limits): LS8-front — filet humain niveau 3 (saisie d'heure de reprise)

UI permettant à l'humain de renseigner l'heure de reprise quand le
niveau 2 détecte une limite sans heure exploitable.

- ports/index.ts : setResumeAt(agentId, resetsAtMs) sur InputGateway.
- adapters/input.ts : setResumeAt → invoke("set_resume_at").
- adapters/mock/index.ts : MockInputGateway.setResumeAt (resumeArmings[]).
- features/agents/useAgents.ts : action setResumeAt (sans mutation optimiste).
- features/agents/AgentLimitBadge.tsx : formulaire de saisie d'heure sur
  l'état suspected sans heure + helper pur timeInputToEpochMs (TODO LS7 retiré).
- features/agents/AgentsPanel.tsx : câblage onSetResumeAt.

Tests AgentLimitBadge.test.tsx mis à jour au nouveau contrat + couverture LS8 ;
typecheck propre, suite agents verte.

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

frontend/src/features/agents/useAgents.ts

@@ -121,6 +121,13 @@ export interface AgentsViewModel {
    * resume had already fired / none was armed).
    */
   cancelResume: (agentId: string) => Promise<boolean>;
+  /**
+   * Human net (level 3, ARCHITECTURE §21.1): arms a resume at a user-chosen
+   * `resetsAtMs` (epoch-ms) for an agent whose limit was suspected without a
+   * reliable time. No optimistic mutation — the backend re-emits
+   * `agentResumeScheduled`, which flips the badge to the nominal countdown.
+   */
+  setResumeAt: (agentId: string, resetsAtMs: number) => Promise<void>;
 }
 
 function describe(e: unknown): string {
@@ -447,6 +454,19 @@ export function useAgents(projectId: string): AgentsViewModel {
     [input],
   );
 
+  const setResumeAt = useCallback(
+    async (agentId: string, resetsAtMs: number): Promise<void> => {
+      // No optimistic mutation: the backend re-emits `agentResumeScheduled`,
+      // which the subscription folds into `limitByAgent` (badge → countdown).
+      try {
+        await input?.setResumeAt(agentId, resetsAtMs);
+      } catch (e) {
+        setError(describe(e));
+      }
+    },
+    [input],
+  );
+
   return {
     agents,
     selectedAgentId,
@@ -468,5 +488,6 @@ export function useAgents(projectId: string): AgentsViewModel {
     launchAgent,
     stopAgent,
     cancelResume,
+    setResumeAt,
   };
 }