Rename the trigger node type to debounce, migrating stored flows

The store rewrites `"type": "trigger"` to `debounce` in every published and
draft flow when it opens, bumps the version and commits once. No alias stays
behind, so `trigger` is now an unknown type.

docs/reference/node-types.md

@@ -187,11 +187,12 @@ Timers wait until their deadline; busy workers can delay execution.
     Batch flows reject rate-limited non-streaming ports. Runs have no live
     timer to release a held value.
 
-### Trigger
+### Debounce
 
-**`trigger`** — send one value now and another once things go quiet. Despite
-the name, a debounce and hold rather than a scheduler: everything it sends
-starts from a value arriving. For a cron tick, see [`inject`](#inject).
+**`debounce`** — send one value now and another once things go quiet. A
+debounce and hold rather than a scheduler: everything it sends starts from a
+value arriving. For a cron tick, see [`inject`](#inject). Node-RED calls this
+node *trigger*.
 
 | Setting | Default | Notes |
 |---|---|---|
@@ -363,7 +364,7 @@ Each record in `actions` contains `message`, `value`, `applied`, `delay_s`,
 applied. Keep `apply=false` while checking how the model interprets commands.
 
 A call with a delay ("in 10m") is held by the engine's work queue, like the
-Trigger node's second value: it survives a restart where the queue is in
+Debounce node's second value: it survives a restart where the queue is in
 Redis, and not otherwise.
 
 The node adds default devices to the model's view for missing expected devices.