fix(coding-agent): align ToolDefinition.execute signature with AgentTool

BREAKING CHANGE: ToolDefinition.execute parameter order changed from
(id, params, onUpdate, ctx, signal) to (id, params, signal, onUpdate, ctx).

This aligns with AgentTool.execute so wrapping built-in tools no longer
requires parameter reordering. Update extensions by swapping signal and
onUpdate parameters.

packages/coding-agent/examples/extensions/tool-override.ts

@@ -72,7 +72,7 @@ export default function (pi: ExtensionAPI) {
 			"Read the contents of a file with access logging. Some sensitive paths (.env, secrets, credentials) are blocked.",
 		parameters: readSchema,
 
-		async execute(_toolCallId, params, _onUpdate, ctx) {
+		async execute(_toolCallId, params, _signal, _onUpdate, ctx) {
 			const { path, offset, limit } = params;
 			const absolutePath = resolve(ctx.cwd, path);