v0.172.0 — R-75: canonical import root, catalog-derived skeleton, import surfaces

${IMPORT_PATH} = <system namespace root>/userdata/import — ONE drop-zone per box,
on the system drive, injected at BOTH compose-env builders with NO per-drive
fallback (unresolvable leaves it unset so compose fails loudly rather than
quietly building a second, dead drop-zone).

Third BindRoot (RootImport) + Import list in BackupSpec, extended through
ValidateBackupSpec/ClassifyBinds. Load-bearing: a stale `userdata: import/<app>`
entry against the moved bind would be a WHOLE-BLOCK reject, taking the app's
mandatory hdd classification with it.

Exhaustive-root audit: resolveAbs/structuralGuard/ComputeCaptureSet/
ComputeFabBuckets now take importRoot explicitly (an import bind resolved
against hddPath would name a directory on the wrong drive); unresolvable is
refused loudly into Skipped. GetImportRoot added to both provider interfaces.

Catalog-derived skeleton: UserdataSkeleton() -> UserdataSkeletonCarry() +
BuildUserdataSkeleton(), SORTED. The carry-list makes zero-removals true by
construction (`documents` is in no catalog app but on both boxes) and is the
fresh-box floor. The sort is not tidiness: the naive map-order derivation
measured 20 distinct outputs from 20 identical runs, which with fbNeedsRecreate
is a fleet-wide FileBrowser restart loop.

One authoritative compose parser: ParseComposeUserdataMounts now delegates to
ParseComposeClassifiableBinds. Import root excluded from per-app migration.

Surfaces: FileBrowser /srv/beolvasas source; app-page "Hova tegyem a fajlokat?"
with PathEscape deep links (never QueryEscape) and class-driven copy;
data_paths: annotation with the Fork-3 asymmetry; system-owned beolvasas SMB
share refused server-side at handler AND store, button omitted in template.

Caught on the way: the sharing template's row struct was function-local, so
adding {{if .System}} would have 500'd every share row. ShareRow is now
package-level and the render test uses the handler's own type.

Tests 915 -> 949, all green. MinAgent unchanged.

controller/internal/stacks/infra.go

@@ -150,10 +150,12 @@ func (m *Manager) ensureFileBrowser(dir string) error {
 	if err := os.MkdirAll(dir, 0o755); err != nil {
 		return fmt.Errorf("mkdir: %w", err)
 	}
-	// Initial render: no storage mounts yet (web.SyncFileBrowserMounts fills them in on the first
-	// storage-path change and owns all later regeneration).
+	// Initial render: no storage mounts yet, and no import source either (web.SyncFileBrowserMounts
+	// fills both in on the first storage-path change and owns all later regeneration). Rendering the
+	// import source here without its bind would produce a source with no path behind it — a broken
+	// sidebar entry — so both halves are deliberately deferred to the same place.
 	compose := infra.RenderFileBrowserCompose(m.cfg.Customer.Domain, nil)
-	config := infra.RenderFileBrowserConfig(nil)
+	config := infra.RenderFileBrowserConfig(nil, false)
 	if err := os.WriteFile(composePath, []byte(compose), 0o644); err != nil {
 		return fmt.Errorf("write docker-compose.yml: %w", err)
 	}