feat!: use self-messaging in the counter start operation

BREAKING CHANGE: the bundled counter accepts start instead of send and queues an add message to itself using ctx.this, rather than forwarding to a target actor.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

CHANGELOG.md

@@ -6,6 +6,8 @@ All notable changes to this project will be documented in this file.
 
 ### Changed
 
+- Change the bundled counter's `send` operation to `start`, which queues an
+  increment to itself using `ctx.this`.
 - **Breaking:** Protocol v5 adds actor log thresholds to snapshots, guarded
   editing operations, and opt-in log-history/follow operations and notifications.
 - Move image sources and actors into a dedicated Runa Activity Bar sidebar,

runa-std/actors/counter.rn

@@ -1,6 +1,6 @@
 pub fn handle(ctx, state, sender, message) {
-    if message.op == "send" {
-        ctx.send(message.target, #{op: "add", value: message.value});
+    if message.op == "start" {
+        ctx.send(ctx.this, #{op: "add", value: 1});
         state + 1
     } else if message.op == "add" {
         state + message.value