wiki: Dingtian relay decision, HTTP-over-MQTT, unmanned direction

- dingtian-relay: relay+input controller (4ch on hand). Inputs are decoupled
  from relays (configurable via input_link_relay) — solves the
  access-controller-button-flow blocker the UHPPOTE couldn't. Full protocol from
  the SDK (UDP string control :60001, `00` status parse, input_link_url push,
  multicast discovery). Driver + hardware test still to build.
- dingtian-vs-mqtt: use direct HTTP/UDP now; MQTT skipped (broker = extra infra
  + failure mode + overkill at one-host/few-devices scale) but kept for later
  multi-lane scale.
- autonomous-direction: record the roadmap to fully unmanned (no booth) and how
  it reshapes the threat model (operator-fraud -> unattended-machine threats),
  makes host-in-the-loop entry mandatory, and raises fail-state stakes.
- threat-model: note the unmanned shift. index + log.

gitignore the vendor SDK (dingtian/, 71MB of binaries/examples) — reference
only, protocol captured in the wiki.

wiki/index.md

@@ -38,6 +38,7 @@ Counts: 1 source · 14 entities · 10 concepts · 2 decision records.
 - [[wiegand]] — reader standard feeding the controller directly (autonomous permit-holder path).
 - [[lpr-camera]] — edge-AI plate recognition; host-side casual-identity source.
 - [[zkteco-controller]] — C3/inBio controller; aux-input path may enable host-in-the-loop (driver TBD).
+- [[dingtian-relay]] — relay+input board; inputs decoupled from relays → solves the button blocker (driver TBD).
 - [[bom]] — reference bill of materials (barrier, loops, controller, readers, payment, host, network).
 
 ## Concepts — foundational forces
@@ -74,3 +75,5 @@ Counts: 1 source · 14 entities · 10 concepts · 2 decision records.
 - [[standing-decisions]] — settled decisions (stack, platform, integrity, access control, readers).
 - [[open-questions]] — 7 open items (6 procurement + JWT key choice); ESP32 device auth deferred.
 - [[access-controller-button-flow]] — ⚠️ BLOCKER: UHPPOTE/ZKTeco on hand can't do ticket-first entry as wired.
+- [[autonomous-direction]] — roadmap: toward fully unmanned (no booth); reshapes threat model + fail-state.
+- [[dingtian-vs-mqtt]] — transport choice: direct HTTP/UDP now, MQTT parked until multi-lane scale.