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

src/beaver_gateway/frontends/markdown/frontend.py

@@ -45,23 +45,10 @@ from fastapi import FastAPI, HTTPException, Request, status
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse, StreamingResponse
 
-from beaver_gateway.core import audit
-from beaver_gateway.core.conversation_store import (
-    diff_and_fork,
-    load_messages,
-    rewrite_messages,
-)
-from beaver_gateway.core.turn_capture import TurnCapture
-from beaver_gateway.core.turn_record import TurnRecord
-from beaver_gateway.frontends._accumulate import StreamAccumulator
-from beaver_gateway.frontends._auth import require_token
-from beaver_gateway.frontends._sse import (
-    KEEPALIVE,
-    SSE_HEADERS,
-    events_with_heartbeat,
-    sse_pack,
-)
+from beaver_gateway.backends.capture import TurnCapture
+from beaver_gateway.frontends.accumulate import StreamAccumulator
 from beaver_gateway.frontends.base import Frontend
+from beaver_gateway.frontends.bearer import require_token
 from beaver_gateway.frontends.markdown import parser, renderer
 from beaver_gateway.frontends.markdown.crossfront import CrossFrontendLogger
 from beaver_gateway.frontends.markdown.files import (
@@ -69,12 +56,25 @@ from beaver_gateway.frontends.markdown.files import (
     reattach_frontmatter,
     write_atomic,
 )
+from beaver_gateway.frontends.markdown.history import (
+    diff_and_fork,
+    load_messages,
+    rewrite_messages,
+)
 from beaver_gateway.frontends.markdown.mirror import FRONTEND, ChatMirror
+from beaver_gateway.frontends.sse import (
+    KEEPALIVE,
+    SSE_HEADERS,
+    events_with_heartbeat,
+    sse_pack,
+)
+from beaver_gateway.frontends.turn_record import TurnRecord
+from beaver_gateway.security import audit
 
 if TYPE_CHECKING:
     from collections.abc import AsyncIterator, Callable
 
-    from beaver_gateway.core.kinds import Kind
+    from beaver_gateway.conversations.kinds import Kind
     from beaver_gateway.frontends.base import GatewayRuntime
     from beaver_gateway.storage.models import Conversation, ConversationBinding