feat(6243): a directory moved in the tree keeps its shape judgments

Ledger rows are keyed by path, so after a directory moves the next sync
marks every judged row vanished and lists the same shapes again, unjudged.
move_shapes(project_id, from_path, to_path) re-keys the rows under one path
to the other, in every repo of the project, keeping each row's judgment,
uses edges and history and adding a `moved` event that records the path it
left. A row already at the target is replaced when nobody judged it; a
judged one stands, and the old row is reported in `kept`.

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

src/grimoire/models/code_shape.py

@@ -311,8 +311,9 @@ class CodeShapeConsumer(Base):
 
 
 # What a shape's history records. Not "appeared" — first_seen and
-# created_at already say that on the row; history is for what CHANGED:
-SHAPE_EVENTS = ("classified", "vanished", "reappeared", "drifted")
+# created_at already say that on the row; history is for what CHANGED.
+# A `moved` event carries the path the shape left; the row says where it went.
+SHAPE_EVENTS = ("classified", "vanished", "reappeared", "drifted", "moved")
 
 
 class CodeShapeEvent(Base):
@@ -321,7 +322,7 @@ class CodeShapeEvent(Base):
     "We used #N here from <date>, #M replaced it at commit C, reason R" is a
     question the ledger row alone cannot answer once it has moved on; this
     table keeps each judgment (status, snippet, who, why, at which commit)
-    and each presence change (vanished / reappeared / drifted) as it
+    and each presence change (vanished / reappeared / drifted / moved) as it
     happened. Denormalised path/symbol/kind so a directory's history reads
     without joining; `snippet_id` is deliberately FK-free — history outlives
     the snippet it names, which is the point.