revert: restore misc/build.func and misc/core.func to main state

These error-handler fixes belong to fix/error-handler-recovery, not to
this sources-only branch.

misc/core.func

@@ -490,8 +490,6 @@ log_section() {
 # - Executes command with output redirected to active log file
 # - On error: displays last 20 lines of log and exits with original exit code
 # - Temporarily disables error trap to capture exit code correctly
-# - Saves and restores previous error handling state (so callers that
-#   intentionally disabled error handling aren't silently re-enabled)
 # - Sources explain_exit_code() for detailed error messages
 # ------------------------------------------------------------------------------
 silent() {
@@ -509,23 +507,14 @@ silent() {
     return 0
   fi
 
-  # Save current error handling state before disabling
-  # This prevents re-enabling error handling when the caller intentionally
-  # disabled it (e.g. build_container recovery section)
-  local _restore_errexit=false
-  [[ "$-" == *e* ]] && _restore_errexit=true
-
   set +Eeuo pipefail
   trap - ERR
 
   "$@" >>"$logfile" 2>&1
   local rc=$?
 
-  # Restore error handling ONLY if it was active before this call
-  if $_restore_errexit; then
-    set -Eeuo pipefail
-    trap 'error_handler' ERR
-  fi
+  set -Eeuo pipefail
+  trap 'error_handler' ERR
 
   if [[ $rc -ne 0 ]]; then
     # Source explain_exit_code if needed