tools (volt): checkin_check -- two advisory prose counts: one pinned to a rev, one removed

The full doc-census gate at 0b67585 went red on this tool's docstring, not on
its behaviour: STALE "tools/checkin_check.py:46 files claimed 70 at HEAD --
printed 71". Two unpinned mutable counts over checkins/ were behind it.

1. The A1 rationale said "52 of 70 files faulty ... 12 real name faults".
   Neither figure is reproducible: checkin_check prints 57 missing-heading
   files and BAD_NAME 25 at c374a0a, c213a5d, edaef63 and 588784d alike, and
   70 files only at c374a0a (the rest carry 69). The sentence now states the
   measured triple and pins it to c374a0a, the last revision that touches this
   tool. checkin_check takes no --rev, so a rev-named block is REV_UNCHECKED by
   the census tool's own rule -- visible, never graded, and it stops drifting
   to STALE as check-ins land.

2. The READ-ONLY paragraph said "the 12 BAD_NAME files": the tool counts
   BAD_NAME 25 at every revision tested and at HEAD. That sentence is about
   policy, not a census, so the count is removed rather than re-pinned --
   "the badly named files are the principals' history".

Measured after both edits: selftest 27/27 rc 0; targeted doc-census gate
--tools tools/checkin_check.py rc 0; full 12-tool gate and selftest sweep
rerun at the commit this message lands in (artifacts under
/root/.hermes/wizard-outputs/volt/2026-10-18-vocab-minimal/).

tools/checkin_check.py

@@ -43,9 +43,9 @@ RULES IMPLEMENTED (stated, not implied)
   A1 HEADINGS    missing any of Did / Blocked / Next / Ask. ADVISORY, never a
                  fault and never rc 1: the four-heading sentence entered this
                  tree after the archive does, so grading history by it would
-                 report 52 of 70 files faulty -- noise that buries the 12 real
-                 name faults. It is printed, counted, and carried in --json, and
-                 the summary says which rule it is.
+                 report 57 of 70 files faulty at `c374a0a` -- noise that buries
+                 the 25 name faults. It is printed, counted, and carried in
+                 --json, and the summary says which rule it is.
   A2 GAP         a day inside a handle's own span with no file, and days since
                  the newest file against --today. ADVISORY, per the table's own
                  words: "A lane that stops churning is a lane that needs a
@@ -59,7 +59,7 @@ EXIT CODES (the repo's contract, `tools/selftest_sweep.py`)
      read as UTF-8. Never 1, never a traceback.
 
 READ-ONLY: the only write path is `--json PATH`. It renames nothing -- the
-12 BAD_NAME files are the principals' history, and a tool that renamed them
+badly named files are the principals' history, and a tool that renamed them
 would be editing the record to make its own report green.
 
 USAGE: