feat(rules): always_on rulebook flag + Scribe-first prompt

Adds rulebooks.always_on (migration 0058) and a new list_always_on_rules
MCP tool so a session-start eager pull can fetch standing rules without
needing an active-project notion. Updates _INSTRUCTIONS so Claude calls
the new tool at session start and codifies engineering rules in Scribe
rather than CLAUDE.md / auto-memory.

Seeds FabledSword family rulebook to always_on=true on migrate, matching
its design role as the cross-project standards rulebook.

Frontend: badge in RulebookListPane for always-on rulebooks; toggle in
RulebookDetailPane header bound to a new toggleAlwaysOn store action.

This is S1+S2 of the rules-consolidation plan (Scribe task #508). S3
(project-scoped rules) and S4 (enter_project handshake) follow.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_routes_rulebooks.py

@@ -44,13 +44,34 @@ def test_service_signatures_require_user_id():
         "create_rulebook", "list_rulebooks", "get_rulebook",
         "update_rulebook", "delete_rulebook", "find_rulebook_by_title",
         "create_topic", "list_topics", "get_topic", "update_topic", "delete_topic",
-        "create_rule", "list_rules", "get_rule", "update_rule", "delete_rule",
+        "create_rule", "list_rules", "list_always_on_rules",
+        "get_rule", "update_rule", "delete_rule",
         "subscribe_project", "unsubscribe_project", "get_applicable_rules",
     ):
         sig = inspect.signature(getattr(svc, fn_name))
         assert "user_id" in sig.parameters, f"{fn_name} missing user_id param"
 
 
+def test_rulebook_model_carries_always_on():
+    """Migration 0058 added rulebooks.always_on — verify the model declares it."""
+    from fabledassistant.models.rulebook import Rulebook
+    assert "always_on" in Rulebook.__table__.columns
+    col = Rulebook.__table__.columns["always_on"]
+    assert col.nullable is False
+
+
+def test_update_rulebook_route_accepts_always_on():
+    """PATCH /api/rulebooks/<id> must pass always_on through to the service.
+
+    The handler filters body keys against a whitelist; that whitelist needs to
+    include always_on or toggling from the UI silently drops the field.
+    """
+    import inspect as _inspect
+    from fabledassistant.routes import rulebooks as rb_routes
+    src = _inspect.getsource(rb_routes.update_rulebook)
+    assert "always_on" in src, "update_rulebook handler missing always_on in field whitelist"
+
+
 def test_rule_and_subscription_handlers_callable():
     from fabledassistant.routes import rulebooks as rb_routes
     for name in (