[A13xB0]

For #600. This is the Renode half; the QEMU half needs the fork.

• Renode side: each declared lamp pin's output is connected back to MeshBenchInputs in the generated platform description (gpio1: 3 -> inputs@35). The peripheral is now an IGPIOReceiver. On a change of level it sends an eight-byte 'L' message (pin, level) over the inputs socket it already holds, and re-sends known levels when the workbench connects.
• Workbench side: ButtonSender reads the socket back and keeps each lamp's level and change count. They reach NodeStat.Lamps, nodes.stats (lamps, keyed by pin) and the board view.
  • A watched lamp is drawn lit or unlit.
  • Its row says "lit/off, changed N times", or "never driven".
  • An unwatched lamp is still the outline with "no watcher on this pin".
  • engine.LampsWatched is the one rule that decides which.
• The inputs channel now also opens for a board whose only part is a lamp.

Live test: RAK_4631 v1.17.1 repeater. Both LEDs (pins 35 and 36) change three times at boot and settle off: {"35": {"changes": 3, "lit": false}, "36": {...}}. The repeater build does not flash them on transmit.

Not done:

• QEMU: mb_lamp.c and the machine wiring in the fork, a release, and a pin bump. ESP32 lamps stay "not modelled" until then.
• Draining the battery meter as the run goes on, which the issue mentions as a companion change.