add conversation expire config & user query text to dingtalk card (#2147)

* add conversation expire config

* add user query text to card

* fix(pipeline): move session limit to AI config

* test(pipeline): cover AI session limit config

* refactor(pipeline): merge session expire-time into AI runner stage

Move the session validity duration field out of the standalone
session-limit stage into the runner stage so it actually renders in the
AI tab (the tab only shows the runner stage and the stage matching the
selected runner — any other stage is filtered out). Read path, default
config, metadata description, and tests updated accordingly.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(pipeline): expire conversations from last update time

* fix(n8n): sync generated conversation id into payload

---------

Co-authored-by: RockChinQ <rockchinq@gmail.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/langbot/templates/default-pipeline-config.json

@@ -38,7 +38,8 @@
     },
     "ai": {
         "runner": {
-            "runner": "local-agent"
+            "runner": "local-agent",
+            "expire-time": 0
         },
         "local-agent": {
             "model": {