core/vm's: ensure script state is sent on script exit (#11991)

* Ensure API update is sent on script exit

Add exit-time telemetry handling across scripts to avoid orphaned "installing" records. Introduce local exit_code capture in api_exit_script and cleanup handlers and, when POST_TO_API_DONE is true but POST_UPDATE_DONE is not, post a final status (marking failures on non-zero exit codes, or marking done/failed in VM cleanups based on exit code). Changes touch misc/build.func, misc/vm-core.func and various vm/*-vm.sh cleanup functions to reliably send post_update_to_api on normal or early exits.

* Update api.func

* fix(telemetry): add missing exit codes to explain_exit_code()

- Add curl error codes: 4, 5, 8, 23, 25, 30, 56, 78
- Add code 10: Docker/privileged mode required (used in ~15 scripts)
- Add code 75: Temporary failure (retry later)
- Add BSD sysexits.h codes: 64-77
- Sync error_handler.func fallback with canonical api.func

misc/vm-core.func

@@ -529,9 +529,21 @@ cleanup_vmid() {
 }
 
 cleanup() {
+  local exit_code=$?
   if [[ "$(dirs -p | wc -l)" -gt 1 ]]; then
     popd >/dev/null || true
   fi
+  # Report final telemetry status if post_to_api_vm was called but no update was sent
+  if [[ "${POST_TO_API_DONE:-}" == "true" && "${POST_UPDATE_DONE:-}" != "true" ]]; then
+    if declare -f post_update_to_api >/dev/null 2>&1; then
+      if [[ $exit_code -ne 0 ]]; then
+        post_update_to_api "failed" "$exit_code"
+      else
+        # Exited cleanly but description()/success was never called — shouldn't happen
+        post_update_to_api "failed" "1"
+      fi
+    fi
+  fi
 }
 
 check_root() {