C6B-F1 cause 2: .fab export mount discovery resolves the userdata convention

exportAdapter.GetStackHDDMounts now returns stacks.ExportDataMounts — the
${HDD_PATH} binds UNIONed with the ${USERDATA_PATH} ROOT (captured at the
root, not per-bind, so the manifest's basename keying round-trips through the
existing import mapping without touching restore). Containment-aware dedupe
both directions. The backup-side stackAdapter is intentionally unchanged.
Red-proof: pre-fix behavior fails TestExportDataMounts_UserdataConvention/
MixedBindsUnion/LiteralUserdataBindDeduped (run->fail->revert recorded).

controller/cmd/controller/main.go

@@ -1354,7 +1354,12 @@ func (a *exportAdapter) GetStackHDDMounts(name string) []string {
 	stackDir := filepath.Dir(s.ComposePath)
 	appCfg := stacks.LoadAppConfig(stackDir)
 	if appCfg != nil && appCfg.Env["HDD_PATH"] != "" {
-		return stacks.ParseComposeHDDMounts(s.ComposePath, appCfg.Env["HDD_PATH"])
+		// C6B-F1 (v0.130.0): union ${HDD_PATH} binds + the ${USERDATA_PATH} root. The old
+		// ParseComposeHDDMounts-only call was blind to the standard userdata convention, so
+		// 12/13 needs_hdd catalog apps exported hollow (config-only) bundles. The backup-side
+		// stackAdapter is intentionally NOT changed — the scheduled/tier-2 path copies the
+		// felhom-data namespace wholesale and its mount list is size/inventory display only.
+		return stacks.ExportDataMounts(s.ComposePath, appCfg.Env["HDD_PATH"])
 	}
 	return nil
 }