refactor: split flat core into capability packages, layer the conversations service, English defaults for every model-facing text

src/beaver_gateway/frontends/markdown/mirror.py

@@ -19,8 +19,6 @@ from typing import TYPE_CHECKING, Any
 
 import frontmatter
 
-from beaver_gateway.core.conversation_store import load_messages, rewrite_messages
-from beaver_gateway.core.turn_record import slugify
 from beaver_gateway.frontends.markdown import renderer
 from beaver_gateway.frontends.markdown.crossfront import strip_trailing_user_scaffold
 from beaver_gateway.frontends.markdown.files import (
@@ -28,12 +26,14 @@ from beaver_gateway.frontends.markdown.files import (
     reattach_frontmatter,
     write_atomic,
 )
+from beaver_gateway.frontends.markdown.history import load_messages, rewrite_messages
+from beaver_gateway.frontends.turn_record import slugify
 
 if TYPE_CHECKING:
     from collections.abc import Callable, Sequence
     from pathlib import Path
 
-    from beaver_gateway.core.bus import Event
+    from beaver_gateway.events.bus import Event
     from beaver_gateway.frontends.base import GatewayRuntime
     from beaver_gateway.storage.models import Conversation, ConversationBinding