fix(R-1187 a,b,d,f,g): .fab — links carried and restored safely, FIFOs refused, owners kept, busy and bad-path refusals, postgis + ON_ERROR_STOP

Red-proved (6 tests). Commit only.

controller/internal/appexport/export.go

@@ -728,10 +728,11 @@ func (e *Exporter) exportHDDData(req ExportRequest, dataDir string, manifest *Ma
 		e.debugf("tarring HDD mount: %s → %s (%d exclude(s))", mount, tarPath, len(excludes))
 		tarStart := time.Now()
 		if err := tarDirectoryExcluding(mount, tarPath, excludes); err != nil {
-			// v0.125.0: claim the subdir ONLY on success — a claimed-but-absent tar would trip
-			// the packaging assertion; an honestly-skipped mount stays out of the manifest.
-			e.logger.Printf("[WARN] Export: failed to tar %s (excluded from the bundle): %v", mount, err)
+			// R-1187 (a): a folder that cannot be packed FAILS the export. It used to be left out with a WARN while the
+			// export ended „done" — a bundle silently missing a whole drive folder. Pinned by TestR1187a_*.
+			e.logger.Printf("[WARN] Export: failed to pack %s — the export FAILS rather than leave it out (R-1187 a): %v", mount, err)
 			os.Remove(tarPath)
+			return err
 		} else {
 			manifest.HDDSubdirs = append(manifest.HDDSubdirs, subdir)
 			if info, _ := os.Stat(tarPath); info != nil {