feat: lightweight bootstrap context mode for heartbeat/cron runs (openclaw#26064) thanks @jose-velez

Verified:
- pnpm build
- pnpm check (fails on pre-existing unrelated repo issues in extensions/diffs and src/agents/tools/nodes-tool.test.ts)
- pnpm vitest run src/agents/bootstrap-files.test.ts src/infra/heartbeat-runner.model-override.test.ts src/cli/cron-cli.test.ts
- pnpm test:macmini (fails on pre-existing extensions/diffs import errors; touched suites pass)

Co-authored-by: jose-velez <10926182+jose-velez@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/infra/heartbeat-runner.ts

@@ -743,9 +743,16 @@ export async function runHeartbeatOnce(opts: {
 
     const heartbeatModelOverride = heartbeat?.model?.trim() || undefined;
     const suppressToolErrorWarnings = heartbeat?.suppressToolErrorWarnings === true;
+    const bootstrapContextMode: "lightweight" | undefined =
+      heartbeat?.lightContext === true ? "lightweight" : undefined;
     const replyOpts = heartbeatModelOverride
-      ? { isHeartbeat: true, heartbeatModelOverride, suppressToolErrorWarnings }
-      : { isHeartbeat: true, suppressToolErrorWarnings };
+      ? {
+          isHeartbeat: true,
+          heartbeatModelOverride,
+          suppressToolErrorWarnings,
+          bootstrapContextMode,
+        }
+      : { isHeartbeat: true, suppressToolErrorWarnings, bootstrapContextMode };
     const replyResult = await getReplyFromConfig(ctx, replyOpts, cfg);
     const replyPayload = resolveHeartbeatReplyPayload(replyResult);
     const includeReasoning = heartbeat?.includeReasoning === true;