Add post_progress_to_api lightweight telemetry ping

Introduce post_progress_to_api() in misc/api.func — a non-blocking, fire-and-forget curl ping (gated by DIAGNOSTICS and RANDOM_UUID) that updates telemetry status to "configuring". Wire this progress ping into multiple scripts (alpine-install.func, install.func, build.func, core.func) at key milestones (container start, network ready, customization, creation, cleanup) and replace/deduplicate some earlier post_to_api calls. Also update error_handler.func to always report failures immediately via post_update_to_api to ensure failures are captured even before/after container lifecycle.

misc/build.func

@@ -3660,9 +3660,6 @@ $PCT_OPTIONS_STRING"
       exit 214
     fi
     msg_ok "Storage space validated"
-
-    # Report installation start to API (early - captures failed installs too)
-    post_to_api
   fi
 
   create_lxc_container || exit $?
@@ -3908,6 +3905,7 @@ EOF
   for i in {1..10}; do
     if pct status "$CTID" | grep -q "status: running"; then
       msg_ok "Started LXC Container"
+      post_progress_to_api # Signal container is running
       break
     fi
     sleep 1
@@ -3962,6 +3960,7 @@ EOF
       echo -e "${YW}Container may have limited internet access. Installation will continue...${CL}"
     else
       msg_ok "Network in LXC is reachable (ping)"
+      post_progress_to_api # Signal network is ready
     fi
   fi
   # Function to get correct GID inside container
@@ -4033,6 +4032,7 @@ EOF'
   fi
 
   msg_ok "Customized LXC Container"
+  post_progress_to_api # Signal ready for app installation
 
   # Optional DNS override for retry scenarios (inside LXC, never on host)
   if [[ "${DNS_RETRY_OVERRIDE:-false}" == "true" ]]; then
@@ -4888,6 +4888,9 @@ create_lxc_container() {
     exit 206
   fi
 
+  # Report installation start to API early - captures failures in storage/template/create
+  post_to_api
+
   # Storage capability check
   check_storage_support "rootdir" || {
     msg_error "No valid storage found for 'rootdir' [Container]"
@@ -5417,9 +5420,7 @@ create_lxc_container() {
   }
 
   msg_ok "LXC Container ${BL}$CTID${CL} ${GN}was successfully created."
-
-  # Report container creation to API
-  post_to_api
+  post_progress_to_api # Signal container creation complete
 }
 
 # ==============================================================================