Bulk multi-select actions, barcode format, batch printing, site name on login

Multi-select (Ctrl/Cmd+click toggle, Shift+click range, right-click the
active selection for bulk actions - same conventions as a native file
manager):
- Print Labels (N) / Export CSV (N) for any mix of individually-picked
  assets and whole folders. Labels/export now take asset_ids/folder_ids
  instead of a single asset_id/folder_id.
- Edit Status..., Check Out..., Duplicate, Move to..., and Delete, bulk
  versions of the existing single-asset actions. Checkout/Move modals
  were generalized to accept an array of ids instead of just one; status
  editing got its own lightweight POST /app/assets/{id}/status endpoint
  (assets.SetStatus) so a bulk status change doesn't need to resend every
  other field the way a full PATCH would.

Labels:
- Choose QR (a /scan/<tag> URL, for a phone camera) or Code128 barcode
  (the bare Asset ID, for a USB scanner typing into the search box) via a
  format selector on the print page. New barcodeDataURI using
  github.com/boombuler/barcode alongside the existing QR generator.
- "Start at #" lets printing resume partway into an already-used sheet
  instead of wasting it on a fresh one.
- Added the Avery 5260 label template (same grid as 5160, rounded
  corners, so it isn't flagged approximate).

Also: the configured Site Name now shows on the login page too, not just
the authenticated navbar.

README.md

@@ -106,25 +106,40 @@ types and fields is seeded on first run — feel free to edit or delete it.
   without creating them a login account. A blank password is fine when
   creating one.
 
-## QR asset tags and printable labels
+## QR/barcode asset tags and printable labels
 
-Every asset can have a QR-coded label printed for it: right-click an asset
+Every asset can have a scannable label printed for it: right-click an asset
 for **Print Label**, or right-click a folder for **Print Labels…** (every
-asset in that folder, recursively). The QR code encodes an absolute
-`/scan/<Asset ID>` URL, so scanning it with a phone camera — or a USB
-barcode/QR scanner focused on the browser's address bar — opens straight to
-that asset.
+asset in that folder, recursively). Choose the code format on the print
+page itself:
 
-The print page supports two label sheet layouts, switchable from a dropdown
-on the page itself:
+- **QR code** — encodes an absolute `/scan/<Asset ID>` URL, so scanning it
+  with a phone camera opens straight to that asset.
+- **Barcode (Code128)** — encodes the bare Asset ID, meant for a dedicated
+  USB barcode scanner typing it into whatever's focused (e.g. the app's
+  search box).
 
-- **Avery 5160** (1" x 2-5/8", 30/sheet) — standard address labels, exact
-  published dimensions.
+The print page also supports three label sheet layouts, switchable from a
+dropdown:
+
+- **Avery 5160 / 5260** (1" x 2-5/8", 30/sheet) — standard address labels
+  (5260 is the same grid, just rounded corners), exact published
+  dimensions.
 - **61526** asset tag labels (3/4" x 2", ~48/sheet) — the grid/margins here
   are a best-effort layout, not a verified spec sheet, so print one test
   page on plain paper and check it against a real label before committing a
   full (often non-refundable) sheet.
 
+**Printing a batch without wasting sheet space**: Ctrl/Cmd+click (toggle)
+or Shift+click (range) multiple folders/assets in the tree, the same way
+you would in a file manager, then right-click the selection for **Print
+Labels (N)** — along with **Export CSV (N)**, **Edit Status…**,
+**Check Out…**, **Duplicate**, **Move to…**, and **Delete**, all bulk
+versions of the single-item actions. On the print page itself, **Start at
+#** lets you resume printing partway into an already-used sheet (position 1
+= top-left, counting left-to-right, top-to-bottom) instead of starting a
+fresh one over a few peeled-off labels.
+
 ## CSV import / export
 
 - **Export**: from the tree's right-click menu, or `/export/assets.csv`