feat(ledger): derive readout ranks body-identical groups first; CSS fingerprints are declarations, not selectors (#2872, milestone 294)

The 2026-08 audit consolidated identical bodies under different names and
files (five auth views' CSS, two Workspace formatDate()s, four modal blocks)
while the derive readout led with name groups (to_dict ×25, main ×5, load ×6)
that were convention or coincidence.

- proposal_summary ranks dup:<sha> groups above name groups, wider file spread
  first, and carries `files`; scoped rows (#2869) are in the readout, since
  that is where view-level copies live.
- extract_definitions fingerprints a CSS rule by its declarations — the row
  identity already carries the selector — so .closed-msg / .error-block /
  .success-msg with one body are one dup group. One-time effect: judged css
  rows whose stored fingerprint predates this may show a recheck on the next
  refresh (the judgment stands; re-confirm).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_shape_ledger.py

@@ -317,6 +317,32 @@ def test_derive_groups_copy_before_name_with_floors():
     assert ("i.py", "sym", "one") not in g
 
 
+def test_proposal_summary_ranks_body_identical_groups_first_and_sees_scoped_rows():
+    """#2872: dup groups (the real copies) outrank name groups (usually
+    convention), wider spread first; #2869: scoped rows are in the readout."""
+    from scribe.models.code_shape import CodeShape
+    from scribe.services.shape_ledger import proposal_summary
+
+    def row(path, symbol, group, kind="css", status="scoped"):
+        return CodeShape(project_id=2, repo_key="r", path=path, symbol=symbol, kind=kind,
+                         status=status, proposal_basis="derive", proposal_group=group)
+    rows = [
+        # a name group of 6 across 6 files
+        *[row(f"v/{i}.vue", "status-badge", "name:css:status-badge") for i in range(6)],
+        # a dup group of 3 across 3 files (different selector names, one body)
+        row("v/Login.vue", "closed-msg", "dup:abc"), row("v/Reset.vue", "error-block", "dup:abc"),
+        row("v/Forgot.vue", "success-msg", "dup:abc"),
+        # a dup group of 2 in ONE file — a copy, but not across files
+        row("v/A.vue", "x", "dup:def"), row("v/A.vue", "y", "dup:def"),
+        # judged rows never count
+        row("v/J.vue", "closed-msg", "dup:abc", status="exempt"),
+    ]
+    out = proposal_summary(rows)
+    assert [g["group"] for g in out["derive_groups"]] == ["dup:abc", "dup:def", "name:css:status-badge"]
+    assert out["derive_groups"][0]["files"] == 3 and out["derive_groups"][0]["size"] == 3
+    assert out["derive_groups"][0]["label"] == "closed-msg (identical body)"
+
+
 def test_confirm_requires_a_named_scope():
     import asyncio