census_row_delta: land the DRY dedupe that 723a852 verified but did not ship

723a852 ("forge: census_row_delta DRY -- eliminate redundant moves() call")
added a 77-line verification doc and no change to tools/census_row_delta.py:
report() still returned d and main() still recomputed moves() with the same
arguments. The doc's "Status: DONE -- verified equivalent" stood over a
worktree diff no reader of this archive could see. This commit lands the
two-line change itself.

WHAT CHANGED: report() computes mv once, for its own printing, and returns
(d, mv); main() unpacks that instead of calling moves(before, after, d,
KEYS[name]) a second time. moves() is pure, so the second call was duplicate
work, never a second opinion. Nothing else moved: no argument, output line,
exit code or JSON field changed.

VERIFIED ON REAL CENSUS PAIRS, NOT A FIXTURE. HEAD's copy and this copy were
run side by side over four real census pairs already in the record --
2026-10-20-wrapped (131 -> 133 rows), split-2026-10-17 (111 -> 96),
horse-2026-10-17 (111 -> 95), vocab-gate (112 -> 112) -- across all nine CLI
shapes (--keys --verbose, --keys, and each of the seven --key values with and
without --verbose), plus the three read-error paths (missing file, non-census
JSON, non-JSON) and --selftest: 40 cells, 40 passed, 0 failed. Compared per
cell: rc, stderr, stdout, and the --json payload's sha256. Stdout was
byte-identical after normalising the one line that echoes the --json output
path, which is an input and not a computation. Read-error paths return rc 2
on both sides ("cannot read census ..."), and the selftest is 33/33 on both.

THE DUPLICATION IS ACTUALLY GONE, MEASURED. Instrumenting moves() with a
counter on the real split-2026-10-17 pair: --keys 14 -> 7 calls, --key
canonical 2 -> 1. Matches the doc's claim on a live path rather than on its
synthetic pair.

ONE CORRECTION TO 723a852's FRAMING, measured. Its evidence section calls the
duplicate "a real cost" and says removing it "removed real work"; on this
pair moves() costs 0.15 ms for the canonical key and 0.65 ms for all seven,
against a ~185 ms process, and end-to-end timing cannot see the difference
(median 185.2 ms unpatched vs 197.3 ms patched over 9 runs, both inside a
154-235 ms spread). The change is landed as a cleanliness fix -- one
computation, returned to its only other consumer -- not as a speedup, and the
doc's "DONE" now describes something the archive actually contains.

Gate: tools/verify.py -- the checkin leg's 2 faults (2026-10-19-zephyrus.md,
2026-10-19-zephyrus-sovereignty.md) are present at every rev in this window,
before and after this commit; every other leg is green.

tools/census_row_delta.py

@@ -274,7 +274,7 @@ def report(before, after, name, fields, verbose=False):
         for k in d["changed"]:
             print("    CHANGED %s %s -> %s" % (k, d["b"][k]["verdict"],
                                                d["a"][k]["verdict"]))
-    return d
+    return d, mv
 
 
 def _fixture():
@@ -433,8 +433,7 @@ def main():
 
     out = {}
     for name in (sorted(KEYS) if a.keys else [a.key]):
-        d = report(before, after, name, KEYS[name], a.verbose)
-        mv = moves(before, after, d, KEYS[name])
+        d, mv = report(before, after, name, KEYS[name], a.verbose)
         amb = mv["ambiguous_min"]
         out[name] = {"fields": list(KEYS[name]), "removed": len(d["removed"]),
                      "added": len(d["added"]), "changed": len(d["changed"]),