Dingtian relay driver — resolves the ticket-first entry blocker

The Dingtian board's inputs are independent of its relays (configurable), so a
button on an input can report to the host WITHOUT auto-firing a relay — solving
the access-controller-button-flow blocker the UHPPOTE/ZKTeco couldn't.

packages/devices:
- access-dingtian.ts: `dingtian` access driver implementing AccessControlDevice
  (relay pulse/latch via UDP string protocol :60001), InputDevice (read inputs +
  poll-based press/release events, active-LOW), and the new PreconditionDevice.
- PreconditionDevice capability on the interface: a device can report config it
  requires for parking and optionally fix it. Dingtian checks input_link_relay
  via the HTTP config API and can disable it.
- httpPort config field — the web/config API port is separate from UDP control
  (this unit uses 8080, not the default 80).
- Register dingtian; export driver objects from the package.

Verified on real hardware (DT-R004 @ 10.0.10.172): status read, relay pulse,
input events; disabled input_link_relay via the driver, then confirmed pressing
inputs fires NO relay (0000) — host-in-the-loop entry works.

Config-write gotcha recorded: config_set.cgi requires "command":"setconfig"
injected after "status" (GET omits it) or the POST silently no-ops.

apps/server/scripts/dingtian-test.mjs: status / watch / pulse hardware test.
wiki: dingtian-relay verified; button-flow marked RESOLVED; index + log.

wiki/decisions/access-controller-button-flow.md

@@ -1,17 +1,22 @@
 ---
 type: decision
-tags: [parking, hardware, access-control, blocker, open]
+tags: [parking, hardware, access-control, resolved]
 sources: [parking-system-architecture]
 updated: 2026-06-15
-status: open
+status: settled
 ---
 
-# Blocker: Push-Button → Auto-Open Defeats the Ticket-First Entry Flow
+# Push-Button → Auto-Open: the Ticket-First Entry Blocker (RESOLVED)
 
-> **Procurement-blocking finding (2026-06-15), from on-hardware testing.** The UHPPOTE and
-> ZKTeco access controllers **on hand** cannot, as wired/configured, deliver the required entry
-> flow. This blocks the entry lane and needs a hardware/wiring resolution before that lane ships.
-> Work paused here to focus on the business side. See [[entry-exit-readers]], [[trust-boundary]].
+> **✅ RESOLVED (2026-06-15) by the [[dingtian-relay]] controller.** Its inputs are decoupled from
+> its relays (`input_link_relay` configurable off — done & verified on hardware), so a button on an
+> input reports to the host **without** firing a relay. Host-in-the-loop entry
+> (`button → host → ticket → host opens relay`) now works. The original blocker (below) stands as
+> the record of why the UHPPOTE/ZKTeco units couldn't do it.
+>
+> **Original procurement-blocking finding (2026-06-15), from on-hardware testing:** the UHPPOTE and
+> ZKTeco controllers on hand could not, as wired/configured, deliver the required entry flow.
+> See [[entry-exit-readers]], [[trust-boundary]].
 
 ## The required flow