fix(delegate): flatten content blocks in live overlay tail + AUTHOR_MAP

Follow-up on the cherry-picked content-block fix. _extract_output_tail
(the live subagent overlay) still used crude str(content), which renders
a "[{'type': 'text'...}]" blob and — worse — mislabels a block-wrapped
"Error: ..." result as is_error=False. Route it through the same
_stringify_tool_content helper so error detection and previews work at
both consumer sites.

- delegate_tool.py: _extract_output_tail uses _stringify_tool_content
- tests: add _extract_output_tail content-block test (error detection +
  clean preview)
- release.py: AUTHOR_MAP entry for randomsnowflake (CI gate)

tools/delegate_tool.py

@@ -261,9 +261,11 @@ def _extract_output_tail(
             break
         if not isinstance(msg, dict) or msg.get("role") != "tool":
             continue
-        content = msg.get("content") or ""
-        if not isinstance(content, str):
-            content = str(content)
+        # Flatten content-block lists/dicts to text so the overlay shows real
+        # output (not a "[{'type': 'text'...}]" blob) and error detection can
+        # see markers buried inside content blocks. Crude str() here would
+        # mislabel a block-wrapped "Error: ..." result as is_error=False.
+        content = _stringify_tool_content(msg.get("content") or "")
         is_error = _looks_like_error_output(content)
         tool_name = pending_call_by_id.get(msg.get("tool_call_id") or "", "tool")
         # Preserve line structure so the overlay's wrapped scroll region can