Add channel-2 #command auto-responder (v0.18.0)

Event-driven CommandService dispatches exact case-sensitive #command
matches on COMMAND_CHANNEL (default 2) through a single-registration-point
registry; first command #ping -> #pong!. Replies ride COMMAND_CHANNEL:
directed DM back to the sender when present, else broadcast. Failing
handler/send only logs a warn.

DI: CommandModule's factory injects MeshService and attaches itself via
MeshService.attachCommands() — a constructor-level cycle leaves one side
null in NestJS 12's injector (verified), so no forwardRef is used.

Tests 106 -> 121; docs synced (AGENTS.md, MESHTASTIC.md, README).

src/mesh/mesh.service.ts

@@ -11,6 +11,8 @@ import * as net from 'node:net';
 // type-only import: node:sqlite is only required at runtime by whoever opens a database (mesh.module.ts / tests)
 import type { DatabaseSync } from 'node:sqlite';
 import type * as Proto from '@meshtastic/protobufs';
+// type-only: the instance arrives via attachCommands() in production (command.module.ts) or the constructor in tests — no runtime import cycle with src/commands
+import type { CommandService } from '../commands/command.service.js';
 import { OpencodeService } from '../opencode/opencode.service.js';
 import {
   BROADCAST_ADDR,
@@ -211,11 +213,23 @@ export class MeshService implements OnModuleInit, OnModuleDestroy {
   private db: DatabaseSync | null = null;
   /** In-process opencode notifier for rx texts on the notify channel; null in tests that don't wire one. */
   private readonly opencode: OpencodeService | null;
+  /** Event-driven `#command` auto-responder (COMMAND_CHANNEL); null until wired — via the constructor (tests) or attachCommands() (DI). */
+  private commands: CommandService | null = null;
   private pollTimer: NodeJS.Timeout | null = null;
 
-  constructor(db?: DatabaseSync, opencode?: OpencodeService) {
+  constructor(
+    db?: DatabaseSync,
+    opencode?: OpencodeService,
+    commands?: CommandService,
+  ) {
     this.db = db ?? null;
     this.opencode = opencode ?? null;
+    this.commands = commands ?? null;
+  }
+
+  /** Wire the `#command` auto-responder after construction — used by command.module.ts to break the DI cycle (a constructor-level MeshService <-> CommandService cycle leaves one side null in NestJS's injector). */
+  attachCommands(commands: CommandService): void {
+    this.commands = commands;
   }
 
   private socket: net.Socket | null = null;
@@ -736,6 +750,8 @@ export class MeshService implements OnModuleInit, OnModuleDestroy {
             at: Date.now(),
           });
           this.notifyRx(pkt.channel ?? 0, text, pkt.from, pkt.id, pkt.to);
+          // event-driven #command auto-responder (COMMAND_CHANNEL) — fire-and-forget like the notifier
+          void this.commands?.onRx(pkt.channel ?? 0, text, pkt.from, pkt.id);
         } else if (decoded && decoded.portnum === PORT_POSITION_APP) {
           // live position update: the Position is serialized in Data.payload
           let pos: Proto.Mesh.Position | undefined;