fix(compressor): strip stale handoff prefix on resume; reconcile #26290+#32787 (#35344)

A handoff persisted under an older SUMMARY_PREFIX can be inherited into a
resumed lineage. _strip_summary_prefix only matched the current/legacy
literal, so on re-compaction the old 'resume exactly from Active Task'
directive stayed embedded in the body and kept hijacking replies to new,
unrelated user messages.

- Add _HISTORICAL_SUMMARY_PREFIXES (pre-#35344 prefix) and strip/recognize
  them in _strip_summary_prefix + _is_context_summary_content so resumed
  stale handoffs are re-normalized to the current latest-message-wins prefix.
- Reconcile the overlapping Active Task template edits from the salvaged
  #26290 (reverse-signal cancellation) and #32787 (capture open questions /
  decisions, don't write None too eagerly) — both intents kept.
- Regression coverage in tests/agent/test_resume_stale_active_task.py.
- AUTHOR_MAP entries for both salvaged contributors.

scripts/release.py

@@ -45,6 +45,8 @@ ACP_REGISTRY_MANIFEST = REPO_ROOT / "acp_registry" / "agent.json"
 
 # Auto-extracted from noreply emails + manual overrides
 AUTHOR_MAP = {
+    "zhipengli@thebrainly.ai": "a1245582339",
+    "mathijs.vd.hurk@gmail.com": "mathijsvandenhurk",
     "drpelagik@gmail.com": "SeaXen",
     "lengr@users.noreply.github.com": "LengR",
     "metalclaudbot@gmail.com": "HashClawAI",