Feat: bot message routing (#2100)

* refactor: pipeline routing rules - add routed_by_rule bypass and diagnostic logging

- Add routing rules editor (RoutingRulesEditor component)
- Add routed_by_rule bypass logic in response rules
- Add diagnostic logging for pipeline routing
- Database migration for bot pipeline routing rules
- Extract RoutingRulesEditor component from BotForm
- Revert log levels to debug

* feat: add message_has_element routing rule type

Support routing by message element type (Image, Voice, File, Forward,
Face, At, AtAll, Quote) with eq/neq operators.

* test: add unit tests for pipeline routing rules

20 tests covering _match_operator (eq/neq/contains/not_contains/
starts_with/regex/invalid) and resolve_pipeline_uuid (launcher_type/
launcher_id/message_content/message_has_element/first-match-wins/
skip-invalid/default-operator).

* fix(web): add missing 'message_has_element' to routing rule type validation

The Zod schema and TypeScript type for PipelineRoutingRule.type were
missing the 'message_has_element' variant, causing silent form validation
failure when saving routing rules with this type.

* feat: add pipeline discard functionality and localization support

* feat(web): improve drag-and-drop with DragOverlay, add discard monitoring and pipeline icons

- Add DragOverlay for smooth cursor-following drag in routing rules editor
- Remove transition to eliminate redundant swap animation on drop
- Record discarded messages in monitoring system via _record_discarded_message
- Display pipeline name (Workflow icon) and runner name (Play icon) on session monitor messages
- Show discard badge on discarded messages in session monitor
- Add i18n translations for discarded/userMessage/botMessage

* fix: ensure discarded messages appear in session monitor and improve icons

- Create/update monitoring session for discarded messages so they show in
  the bot session monitor (was only inserting message rows, not sessions)
- Use human-readable 'Discarded' as pipeline_name instead of '__discard__'
- Change runner icon from Play to Bot for better AI Agent semantics

* fix: merge discarded messages into same session and remove session-level pipeline name

- Use LauncherTypes enum for session_id in discarded messages to match
  the format used by monitoring_helper (fixes duplicate sessions)
- Don't overwrite session pipeline info on discard — a session can have
  messages from multiple pipelines
- Remove pipeline_name from session list and chat header since it's
  now shown per-message and a session is no longer single-pipeline

* fix(web): only show save button on config tab in bot detail page

* fix(web): scroll to bottom after messages render in session monitor

---------

Co-authored-by: RockChinQ <rockchinq@gmail.com>

src/langbot/pkg/pipeline/pool.py

@@ -41,6 +41,7 @@ class QueryPool:
         message_chain: platform_message.MessageChain,
         adapter: abstract_platform_adapter.AbstractMessagePlatformAdapter,
         pipeline_uuid: typing.Optional[str] = None,
+        routed_by_rule: bool = False,
     ) -> pipeline_query.Query:
         async with self.condition:
             query_id = self.query_id_counter
@@ -52,7 +53,7 @@ class QueryPool:
                 sender_id=sender_id,
                 message_event=message_event,
                 message_chain=message_chain,
-                variables={},
+                variables={'_routed_by_rule': routed_by_rule},
                 resp_messages=[],
                 resp_message_chain=[],
                 adapter=adapter,