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_pattern_coverage.py

@@ -468,6 +468,11 @@ def test_extract_definitions_fingerprints_each_block():
     # And the identity view is unchanged for the hook mirror.
     from scribe.services.coverage import extract_shapes
     assert extract_shapes(text) == [(d.kind, d.name) for d in extract_definitions(text)]
+    # A CSS rule's fingerprint is its declarations (#2872): the same body
+    # under another selector is the same shape to the derive grouping.
+    css = ".closed-msg {\n  text-align: center;\n  padding: 0.5rem 0;\n}\n.error-block {\n  text-align: center;\n  padding: 0.5rem 0;\n}\n.other {\n  text-align: left;\n}\n"
+    d = {x.name: x for x in extract_definitions(css)}
+    assert d["closed-msg"].body_sha == d["error-block"].body_sha != d["other"].body_sha
 
 
 def test_coverage_line_names_the_proposers_standing():