test(e2e): cover host mode, reusable workflows, scheduling, reconnect and CLI flags (#1347)

Extends the e2e suite with scenarios for host labels, local `workflow_call`, label routing, `runner.capacity`, a dropped and restored connection to Gitea, and the daemon's `--once`, `--labels` and `shutdown_timeout` behaviour.

Stacked on https://gitea.com/gitea/runner/pulls/1346, so its commit shows here until that merges. The new scenarios pass locally against gitea/gitea:latest and main-nightly.

Assisted-by: Codet:codet
Co-authored-by: Zettat123 <[email protected]>
Co-authored-by: bircni <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1347
Reviewed-by: Zettat123 <[email protected]>

e2e/compatibility_test.go

@@ -35,6 +35,15 @@ func TestCompatibility(t *testing.T) {
 	t.Run("ephemeral", testEphemeralRunner)
 	t.Run("failure_paths", testFailurePaths)
 	t.Run("cli_register_daemon", testCLIRegisterDaemon)
+	t.Run("cli_once", testCLIOnce)
+	t.Run("cli_labels_override", testCLILabelsOverride)
+	t.Run("cli_shutdown_drains", testCLIShutdownDrains)
+	t.Run("cli_shutdown_cancels", testCLIShutdownCancels)
+	t.Run("host_mode", testHostMode)
+	t.Run("reusable_workflow", testReusableWorkflow)
+	t.Run("label_routing", testLabelRouting)
+	t.Run("capacity", testCapacity)
+	t.Run("reconnect", testReconnect)
 	t.Run("kubernetes", testKubernetes)
 }