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.

CHANGELOG.md

@@ -23,6 +23,17 @@ hub answers 400 to both and nothing else changes.
   /api/escrow/start` answers 409 with `api.escrow.recovery_offer_open` (hu + en) before anything is staged or started.
   Tests `TestR1219_*` (the bar with a real session, and the same box without an offer as the control), red-proved (bar
   shown, start 200).
+- **R-1187 (P2, `.fab` export/import) — (a), (b), (d), (f), (g):** (a) the export carries a symlink AS A LINK (never its
+  target's bytes) and stops with `err.appexport.kulonleges_fajl` naming the path on a FIFO, socket or device (a FIFO used
+  to hang it); a drive folder that cannot be packed now FAILS the export (it was left out with a WARN while the export
+  ended „done"). (b) the import keeps owners (`Lchown`) and modes and restores a link that stays inside the app's folder;
+  a link pointing outside is refused and listed in a WARN. (d) `StartImport` refuses (`err.appexport.import_foglalt`)
+  while another operation holds the app-stop marker (`BusyWith`). (f) a bundle whose `app.yaml` carries an empty,
+  relative or unclean `HDD_PATH` is refused before anything is touched (`err.appexport.hdd_path_hibas`). (g) the import
+  classifies databases with the backup side's predicate (`appbackup.DBTypeForImage`: postgis, pgvector, timescaledb) and
+  runs `psql -v ON_ERROR_STOP=1`. Tests `internal/appexport/r1187_abdfg_test.go` (6), red-proved with the old behaviour
+  behind the new function shapes (link packing error, a 10-s hang on the FIFO, link not restored, import not refused,
+  bad paths accepted, postgis missed).
 - `settings.RestoreHold.Why()` / `WireReason()`: the hold sentence moved out of `cmd/controller` (`holdWhy` calls it), so
   `--restore-holds` and the hub's list say the same thing.
 - Tests `internal/holdreport/holdreport_test.go` (8): the report field, the daily repeat, cleared once, cleared while