printedparts stage 16: kiosk touch fixes from first hands-on use

The tap-anywhere wedge refocus stole focus from the manual-entry field
the moment it was tapped - the handler now only reclaims focus from
dead space, never from a real control. Manual entry works without a
physical keyboard: badge entry uses the TouchKeypad (an SSO is
digits), and item lookup accepts bare digits resolved by row id - the
digits in a minted code are the id, which also keeps labels printed
under an older prefix scannable after the prefix changes.

docs/PLUGIN-LAB-PRINTEDPARTS.md

@@ -371,6 +371,20 @@ Two more field requests, and the plugin's FIRST incremental migration:
    ACTIVE member of each selected role (role.users backref), deduped with
    the user picks and free-text; settings page gains a role picker.
 
+## Stage 16 (extension) - kiosk touch fixes from first hands-on use
+
+First real touchscreen session found two problems worth their own stage:
+1. Focus steal: the page's tap-anywhere handler refocused the hidden wedge
+   input, yanking focus out of the manual-entry field the moment it was
+   tapped. Guard the handler - never reclaim focus from INPUT/SELECT/
+   TEXTAREA/BUTTON/A targets, only from dead space.
+2. No physical keyboard on a touchscreen: manual fallbacks now use the
+   TouchKeypad. Badge entry is digits (an SSO) so the keypad covers it;
+   item codes are letters+digits, solved server-side instead of building an
+   alphanumeric keyboard - the digits in a minted code ARE the row id, so
+   `/kiosk/item/<digits>` resolves bare digits by id. Bonus: labels printed
+   under an older code prefix keep working after the prefix changes.
+
 ---
 
 ## Where each pattern lives (cheat sheet)