fix(hooks): suppress main session events for silent/delivered hook turns (#20678)

* fix(hooks): suppress main session events for silent/delivered hook turns

When a hook agent turn returns NO_REPLY (SILENT_REPLY_TOKEN), mark the
result as delivered so the hooks handler skips enqueueSystemEvent and
requestHeartbeatNow. Without this, every Gmail notification classified
as NO_REPLY still injects a system event into the main agent session,
causing context window growth proportional to email volume.

Two-part fix:
- cron/isolated-agent/run.ts: set delivered:true when synthesizedText
  matches SILENT_REPLY_TOKEN so callers know no notification is needed
- gateway/server/hooks.ts: guard enqueueSystemEvent + requestHeartbeatNow
  with !result.delivered (addresses duplicate delivery, refs #20196)

Refs: https://github.com/openclaw/openclaw/issues/20196

* Changelog: document hook silent-delivery suppression fix

---------

Co-authored-by: Vincent Koc <vincentkoc@ieee.org>

src/gateway/server/hooks.ts

@@ -86,11 +86,13 @@ export function createGatewayHooksRequestHandler(params: {
         const summary = result.summary?.trim() || result.error?.trim() || result.status;
         const prefix =
           result.status === "ok" ? `Hook ${value.name}` : `Hook ${value.name} (${result.status})`;
-        enqueueSystemEvent(`${prefix}: ${summary}`.trim(), {
-          sessionKey: mainSessionKey,
-        });
-        if (value.wakeMode === "now") {
-          requestHeartbeatNow({ reason: `hook:${jobId}` });
+        if (!result.delivered) {
+          enqueueSystemEvent(`${prefix}: ${summary}`.trim(), {
+            sessionKey: mainSessionKey,
+          });
+          if (value.wakeMode === "now") {
+            requestHeartbeatNow({ reason: `hook:${jobId}` });
+          }
         }
       } catch (err) {
         logHooks.warn(`hook agent failed: ${String(err)}`);