feat(family): the shape ledger judges against family ideas, across languages (milestone 463 step 5, #4991)

- classify_shapes takes idea_id: the shape is judged against the idea's
  reference in its language, or its first.
- A shape classified against a canon idea's reference moves the project's
  adoption row (instance -> adopted, variant -> variant). Withdrawing the
  shapes that gave an answer returns it to unassessed. This runs on
  classify_shapes, the sweep, confirm_proposals and the coverage refresh.
- assess and undo refuse an answer the shapes contradict. A conflict
  resolution re-judges the variant shapes on both sides.
- The proposer's family arm offers a canon idea's reference on a shared
  platform, in any language. It proposes only when the reference is the top
  hit over every readable snippet and scores at least 0.70. The pairs this
  was measured on are recorded beside _FAMILY_FLOOR. The proposer is now v6.
- The matrix cell shows the code that answers it.

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

tests/test_divergence_meaning_gate.py

@@ -64,14 +64,14 @@ def _patch(mock: AsyncMock):
 
 async def test_a_hit_returns_the_canon() -> None:
     with _patch(_hits((0.88, CANON))):
-        assert await _semantic_canon(1, BODY, {CANON}) == (CANON, 0.88)
+        assert await _semantic_canon(1, BODY, {CANON}) == (CANON, 0.88, "semantic")
 
 
 async def test_an_allowed_canon_below_the_top_hit_still_wins() -> None:
     """The scan is over the whole result set, so a disallowed snippet ranking
     first does not hide an allowed one behind it."""
     with _patch(_hits((0.95, OTHER), (0.83, CANON))):
-        assert await _semantic_canon(1, BODY, {CANON}) == (CANON, 0.83)
+        assert await _semantic_canon(1, BODY, {CANON}) == (CANON, 0.83, "semantic")
 
 
 async def test_a_miss_is_none_and_nothing_more() -> None: