feat: Add Agent Logs tab to task slide-over

Add getTaskAgent tRPC procedure to find the most recent agent for a task.
TaskSlideOver now has Details/Agent Logs tabs — logs tab renders
AgentOutputViewer when an agent exists, or an empty state otherwise.

apps/server/trpc/routers/agent.ts

@@ -184,6 +184,17 @@ export function agentProcedures(publicProcedure: ProcedureBuilder) {
         return candidates[0] ?? null;
       }),
 
+    getTaskAgent: publicProcedure
+      .input(z.object({ taskId: z.string().min(1) }))
+      .query(async ({ ctx, input }): Promise<AgentInfo | null> => {
+        const agentManager = requireAgentManager(ctx);
+        const all = await agentManager.list();
+        const matches = all
+          .filter(a => a.taskId === input.taskId)
+          .sort((a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime());
+        return matches[0] ?? null;
+      }),
+
     getActiveConflictAgent: publicProcedure
       .input(z.object({ initiativeId: z.string().min(1) }))
       .query(async ({ ctx, input }): Promise<AgentInfo | null> => {