fix(rules): resolve the Rule forward ref for ruff and readers (#3030)

F821: the quoted `"Rule"` in semantic_search_rules' return annotation
evaluates fine at runtime — a string inside a subscript is a value, not a name
lookup — but it points at nothing a reader or a type checker can follow, which
is what ruff is objecting to and it is right to.

A TYPE_CHECKING import resolves it at zero runtime cost, while the real import
stays inside the function so this module still does not pull in the rulebook
models. Placed after the import block, where isort wants the guard.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/scribe/services/embeddings.py

@@ -16,6 +16,8 @@ import os
 
 from collections.abc import Sequence
 
+from typing import TYPE_CHECKING
+
 from sqlalchemy import delete, or_, select
 
 from scribe.models import async_session
@@ -23,6 +25,9 @@ from scribe.models.embedding import NoteEmbedding, RuleEmbedding
 from scribe.models.note import Note
 from scribe.services.access import notes_visibility_clause
 
+if TYPE_CHECKING:  # resolves the Rule forward ref without importing at runtime
+    from scribe.models.rulebook import Rule
+
 logger = logging.getLogger(__name__)
 
 # Minimum cosine similarity to include a note in context results.