Add cleanup handler for failed LXC installations

Introduces the cleanup_failed_lxc function to prompt for and remove broken containers after failed LXC installs. Updates catch_errors to invoke this cleanup on EXIT, ensuring failed containers are handled automatically or with user confirmation.

misc/error_handler.func

@@ -224,7 +224,81 @@ error_handler() {
 }
 
 # ==============================================================================
-# SECTION 3: SIGNAL HANDLERS
+# SECTION 3: CLEANUP HANDLERS
+# ==============================================================================
+
+# ------------------------------------------------------------------------------
+# cleanup_failed_lxc()
+#
+# - Cleanup handler for failed LXC installations
+# - Only prompts during install phase (when CTID is set)
+# - Asks user if they want to remove the broken container
+# - 60 second timeout - auto-removes if no response
+# - Stops and destroys container on timeout or confirmation
+# - Silent if CTID not set or container doesn't exist
+# ------------------------------------------------------------------------------
+cleanup_failed_lxc() {
+  local exit_code=$?
+
+  # Only cleanup on error and during install (CTID must be set)
+  if [[ $exit_code -eq 0 || -z "${CTID:-}" ]]; then
+    return 0
+  fi
+
+  # Check if container exists
+  if ! pct status "$CTID" &>/dev/null; then
+    return 0
+  fi
+
+  # Prompt user for cleanup
+  if declare -f msg_warn >/dev/null 2>&1; then
+    msg_warn "Installation failed for container ${CTID}"
+  else
+    echo -e "\n${YW}[WARN]${CL} Installation failed for container ${CTID}"
+  fi
+
+  # Ask for confirmation with 60s timeout
+  local response
+  echo -en "${YW}Remove broken container ${CTID}? (Y/n) [auto-remove in 60s]: ${CL}"
+
+  if read -t 60 -r response; then
+    # User provided input within timeout
+    if [[ -z "$response" || "$response" =~ ^[Yy]$ ]]; then
+      # Empty (Enter) or Y/y = remove
+      :
+    elif [[ "$response" =~ ^[Nn]$ ]]; then
+      # N/n = keep for debugging
+      if declare -f msg_info >/dev/null 2>&1; then
+        msg_info "Container ${CTID} kept for debugging"
+      else
+        echo -e "${YW}Container ${CTID} kept for debugging${CL}"
+      fi
+      return 0
+    fi
+  else
+    # Timeout reached - auto-remove
+    echo -e "\n${YW}No response - auto-removing container${CL}"
+  fi
+
+  # Cleanup confirmed or timeout
+  if declare -f msg_info >/dev/null 2>&1; then
+    msg_info "Removing container ${CTID}"
+  else
+    echo -e "${YW}Removing container ${CTID}...${CL}"
+  fi
+
+  pct stop "$CTID" &>/dev/null || true
+  pct destroy "$CTID" &>/dev/null || true
+
+  if declare -f msg_ok >/dev/null 2>&1; then
+    msg_ok "Container ${CTID} removed"
+  else
+    echo -e "${GN}Container ${CTID} removed${CL}"
+  fi
+}
+
+# ==============================================================================
+# SECTION 4: SIGNAL HANDLERS
 # ==============================================================================
 
 # ------------------------------------------------------------------------------
@@ -275,7 +349,7 @@ on_terminate() {
 }
 
 # ==============================================================================
-# SECTION 4: INITIALIZATION
+# SECTION 5: INITIALIZATION
 # ==============================================================================
 
 # ------------------------------------------------------------------------------
@@ -288,7 +362,7 @@ on_terminate() {
 #   * set -u: (optional) Exit on undefined variable (if STRICT_UNSET=1)
 # - Sets up traps:
 #   * ERR → error_handler
-#   * EXIT → on_exit
+#   * EXIT → on_exit (+ cleanup_failed_lxc if in install context)
 #   * INT → on_interrupt
 #   * TERM → on_terminate
 # - Call this function early in every script
@@ -299,7 +373,7 @@ catch_errors() {
     set -u
   fi
   trap 'error_handler' ERR
-  trap on_exit EXIT
+  trap 'cleanup_failed_lxc; on_exit' EXIT
   trap on_interrupt INT
   trap on_terminate TERM
 }