wiki: ER80 protocol = HTTP GET poll + JSON verdict (from QRCode SDK)

The QRCode SDK v1.6.5 settles the reader protocol (supersedes the earlier
serial guess). On each scan the reader HTTP-GETs the host
(/qa/mcardsea.php?cardid&mjihao&cjihao&status&time); the host replies JSON
{data:[{...,status,output}],code:0}. Reply status 1=valid(beep 2x)/0=invalid
(beep 1x); output 0=Access/1=WG26/2=WG34; time syncs the clock. The GET's status
low digit is the direction (1=in/0=out).

Key: the beep/accept is decided by the SERVER REPLY, not locally -- the 'no
beep' during bring-up was a plain-text reply, not a scan failure. Host-in-the-
loop and synchronous. 'Server language' only selects the URL path; transport is
plain HTTP.

New source page qrcode-sdk; updated gee-qr-er80 (protocol resolved), index.

wiki/index.md

@@ -7,7 +7,7 @@ updated: 2026-06-14
 # Index
 
 Content catalog for the wiki. Start at [[overview]]. Maintained on every ingest.
-Counts: 2 sources · 19 entities · 24 concepts · 5 decision records.
+Counts: 3 sources · 19 entities · 24 concepts · 5 decision records.
 
 ## Overview & navigation
 - [[overview]] — the top-level synthesis and entry point.
@@ -17,6 +17,7 @@ Counts: 2 sources · 19 entities · 24 concepts · 5 decision records.
 ## Sources
 - [[parking-system-architecture]] — design notes: stack, threat model, devices, UHPPOTE, ESP32, readers, BOM, open decisions.
 - [[gee-qr-er80]] — datasheet: GEE QR access reader (QR/DM/1D; Wiegand/RS-232/485/USB/TCP; Linux).
+- [[qrcode-sdk]] — QRCode SDK v1.6.5: the reader's HTTP-GET-poll protocol + JSON verdict (beep/output).
 
 ## Entities — technology stack
 - [[technology-stack]] — the full stack table; all MIT/Apache/BSD, chosen to avoid lock-in.