fix: align telemetry client payload and dimensions with backend schema

Restructure the TelemetryClient to send the correct backend envelope
format ({app, schemaVersion, installId, events: [{name, occurredAt, dimensions}]})
instead of the old per-event format. Update all event dimension names
to match the backend registry (agent_role, adapter_type, error_code, etc.).

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/__tests__/issue-telemetry-routes.test.ts

@@ -100,7 +100,7 @@ describe("issue telemetry routes", () => {
 
     expect(res.status).toBe(200);
     expect(mockTrackAgentTaskCompleted).toHaveBeenCalledWith(expect.anything(), {
-      adapterType: "codex_local",
+      agentRole: "codex_local",
     });
   });