ci: make public-hygiene-lint green

[MattJackson]

public-hygiene-lint was RED on main in this repo. Every hit is fixed by rewriting the text to
state the BEHAVIOUR rather than our internal process. No allow markers were added anywhere in
this change: a blanket allow would turn the gate into decoration.

Hits found on main, and the decision for each

• .github/scripts/next-version.sh + .github/workflows/release-selftest.yml [internal-issue-id]
  cited an internal guard id. REWRITTEN: id dropped.
• store-mysql/src/lib.rs [internal-issue-id] cited an internal audit command as the provenance of
  a documented gap. REWRITTEN: the gap and its reasoning are fully stated in the same comment, so
  the provenance added nothing a reader can open.
• store-mysql/src/lib.rs [editor-directed] addressed the next editor ("do not "fix" this with a
  lock"). REWRITTEN as a statement about the code: a lock is not the fix, and the comment already
  explains why.
• store-mysql/src/lib.rs [authoring-meta] said the redesign was "out of scope for this pass".
  REWRITTEN to state the durable fact: the redesign has not been done.

Red before green

Same invocation CI uses. Output is ASCII-folded for this description; the runs are verbatim
otherwise.

Before (on main)

$ python3 busbarAI/scripts/public-hygiene-lint.py --root .
== public-hygiene: what a customer reads, in . ==
  scanned 18 file(s) via git ls-files; 11 rules applied

  [authoring-meta] meta-commentary on how the change was authored - 1 hit(s)
      why: narrates the authoring transaction (who asked, what was in scope, who decides); a shipped file should carry no evidence that it was commissioned at all
      store-mysql/src/lib.rs:299: /// provenance marker) - real redesign work, out of scope for this pass. OPERATIONAL MITIGATION

  [editor-directed] prose addressed to whoever edits the file next - 1 hit(s)
      why: speaks to a future maintainer instead of describing the software; the object is the FILE, which is what keeps invariant prose like `do not touch the breaker` silent
      store-mysql/src/lib.rs:283: /// adversarial design reviews - do not "fix" this with a lock; both reviews independently showed

  [internal-issue-id] internal issue / task / audit-round identifier - 3 hit(s)
      why: cites a tracker or audit artifact the reader cannot open; `task #141` and `R27 #8` shipped inside operator-facing API documentation
      .github/scripts/next-version.sh:5: # release automation can't silently rot (guard #135.8). Prints "v<MAJOR>.<MINOR>.<PATCH>" to stdout.
      .github/workflows/release-selftest.yml:1: # CI self-test for the release-on-upstream version-compute logic (guard #135.8).
      store-mysql/src/lib.rs:282: /// KNOWN, DOCUMENTED, NOT-YET-CLOSED GAP (found in `/codeaudit`, confirmed by two independent

== result ==
  18 public file(s) scanned against 11 rules - 5 hit(s), 0 allowed
  public-hygiene-lint FAILED
  These lines describe how the software was BUILT, not what it does, in files a
  customer can read. Rewrite the text to state the behaviour or the invariant; if a
  line is genuinely legitimate, mark it:
    # public-hygiene-lint: allow - <why this text belongs in a public file>

After (this branch)

$ python3 busbarAI/scripts/public-hygiene-lint.py --root .
== public-hygiene: what a customer reads, in . ==
  scanned 18 file(s) via git ls-files; 11 rules applied

== result ==
  18 public file(s) scanned against 11 rules - 0 hit(s), 0 allowed
  public-hygiene-lint passed