Model rules: who a chat's model may bring into a conversation

Rules read from the main model decide who it is offered as a crowd member,
a friend and on its roster; any-to-any with denies by default, or
none-to-none with allows. The crowd picker names what it holds back and
why, and a model held back only by a person's own rule -- or by anything,
with the new rules.override -- can still be added by hand. Another data
group is now a deny that an explicit rule opens. Admin -> Model rules and
a card in Settings, each with a matrix drawn by the enforcing function.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/lembas/db/models/__init__.py

@@ -84,6 +84,7 @@ from lembas.db.models.schedule import (
 )
 from lembas.db.models.setting import Setting
 from lembas.db.models.suggestion import Suggestion
+from lembas.db.models.talk import ANY_MODEL, EFFECT_ALLOW, EFFECT_DENY, EFFECTS, TalkRule
 from lembas.db.models.tool import (
     RESPONSE_JSON,
     RESPONSE_MODES,
@@ -170,6 +171,11 @@ __all__ = [
     "Connection",
     "DEFAULT_GROUP",
     "DataGroup",
+    "ANY_MODEL",
+    "EFFECT_ALLOW",
+    "EFFECT_DENY",
+    "EFFECTS",
+    "TalkRule",
     "InDataGroup",
     "CustomTool",
     "CHUNK_DOCUMENT",