Dingtian input HTTP-push to backend (no polling)

The device pushes button events to the backend via its Input Link URL feature;
the backend decides. No polling — the chosen entry architecture.

packages/devices:
- dingtian driver: configureInputPush() writes the device's input_link_url
  config (per-input server/port/path, en=1, active-LOW, plain HTTP) so each
  input HTTP-GETs the backend on press/release. Extracted #readConfig/#writeConfig
  (with the required command:setconfig injection + post-write reset tolerance).

apps/server:
- routes/devices.ts: public GET/POST
  /api/devices/dingtian/:deviceId/input/:n/{on,off} — translates a device push
  into an internal device event. Not behind cookie/CSRF (machine call from the
  device); trust comes from the signed event log, not this request.
- device-events.ts: internal EventEmitter bus so the entry flow subscribes to
  input events without coupling to HTTP. Wired into the server.

Verified on hardware: configured the device, then real presses on all 4 inputs
pushed to the backend (input N on+off, source = device IP). No polling.

wiki: device-input-flow concept (path + trust model for the flat/no-VLAN
network); dingtian-relay updated; index + log.

wiki/index.md

@@ -54,6 +54,7 @@ Counts: 1 source · 14 entities · 10 concepts · 2 decision records.
 - [[device-adapter-pattern]] — business logic talks to interfaces; swap hardware → new adapter.
 - [[device-registry]] — catalog of selectable drivers per category (admin-configurable).
 - [[first-run-setup]] — admin assigns devices per lane from the catalog at install.
+- [[device-input-flow]] — button → device push → backend decides → relay; backend is source of truth.
 - [[device-discovery]] — optional driver capability to scan the LAN (no current driver uses it; UHPPOTE was the example).
 - [[barrier-not-a-door]] — never timed-close a barrier; safety lives in barrier firmware.
 - [[trust-boundary]] — the core fork: network vs. device; auditable vs. unforgeable.