wiki: ingest GEE-QR-ER80 QR access reader datasheet

The reader on hand is a GEE-QR-ER80 QR/DataMatrix/1D barcode access reader
(not an EM4100 prox-card reader as first guessed). Interfaces: Wiegand 26/34,
RS-232, RS-485, USB, TCP/IP; 4-15 VDC; Linux-supported. Variant on hand: -Q-W
(QR scanner, Wiegand/RS-232/485).

This is the QR-ticket scanner the design already needed: a host-side reader
whose scans become read-bus events consumed by the (already-built) exit flow
and QR-permit path. Prefer RS-232/485 over Wiegand (Wiegand can't carry a
variable-length QR string; autonomy is moot with the no-ACL Dingtian).

New source + entity pages; updated ticket-encoding, entry-exit-readers, index.
Open (blocks the adapter): the RS-232/485 frame + baud (ASCII CR/LF expected).

wiki/concepts/ticket-encoding.md

@@ -37,6 +37,9 @@ must have:
 - The **scanner is a device behind an adapter** ([[device-adapter-pattern]]): a new `ReaderDevice`
   kind (QR/barcode imager) — likely the same `IdentitySource = "ticket"` / `"qr"` path. Keeps the
   app device-agnostic; hardware model is procurement ([[bom]], [[open-questions]]).
+  - **On hand:** the **[[gee-qr-er80]]** QR access reader (`-Q-W`: QR scanner, Wiegand/RS-232/RS-485,
+    Linux-supported) — the concrete scanner for this path. A serial `ReaderDevice` adapter feeds the
+    `read` bus; pending the reader's RS-232 frame/baud (see [[gee-qr-er80]] open questions).
 
 ## Ticketless alternative (plate as the ticket)