refactor: centralize cron session metadata keys

nanobot/webui/transcript.py

@@ -18,6 +18,7 @@ from loguru import logger
 
 from nanobot.config.paths import get_webui_dir
 from nanobot.session.manager import SessionManager
+from nanobot.webui.metadata import WEBUI_MESSAGE_SOURCE_METADATA_KEY, WEBUI_TURN_METADATA_KEY
 
 WEBUI_TRANSCRIPT_SCHEMA_VERSION = 3
 WEBUI_FORK_MARKER_EVENT = "fork_marker"
@@ -29,8 +30,6 @@ _TRANSCRIPT_SEGMENT_RE = re.compile(r"^\d{6}\.jsonl$")
 _DEFAULT_TRANSCRIPT_PAGE_LIMIT = 160
 _MAX_TRANSCRIPT_PAGE_LIMIT = 1000
 _WEBUI_TURN_ID_RE = re.compile(r"^[A-Za-z0-9._:-]{1,128}$")
-WEBUI_TURN_METADATA_KEY = "webui_turn_id"
-WEBUI_MESSAGE_SOURCE_METADATA_KEY = "_webui_message_source"
 _MARKDOWN_LOCAL_IMAGE_RE = re.compile(
     r"!\[([^\]]*)\]\((<[^>]+>|[^)\s]+)(\s+(?:\"[^\"]*\"|'[^']*'))?\)"
 )