refactor(doc-truth): consolidate the two #176 guards into one unified check-doc-truthing.sh

[hyperpolymath]

What

Consolidates the two doc-truthing guards that briefly co-existed on main after #476 (DOC-16) and #475 (DOC-17) landed in parallel, into a single unified guard — so neither lingers as a near-duplicate.

Before: tools/check-doc-truthing.sh (banner/primacy/mirror presence) and tools/check-doc-overclaims.sh (over-claim ratchet) — two near-identically-named scripts, two CI steps, two ledger rows.

After: one toolchain-free gate doing both, "best of both":

• Keeps feat(doc-truthing): in-repo DOC-04/05 guard + ADR-019 record (Refs #175 #176 #260) #476's fail-accumulator + note() structure, so a single run reports all problems together (presence failures and ratchet hits) rather than failing fast.
• Absorbs feat(doc-truth): over-claim ratchet (DOC-17) complementing #476's banner guard (Refs #176) #475's over-claim ratchet (DOC-08/09) as a fourth check feeding the same accumulator, plus the --update re-baseline mode and the frozen tools/doc-overclaims.allow baseline (13 signatures, unchanged).
• Presence-checking covers the banners (where production-ready legitimately appears); the frozen baseline adds phrase detection without false positives.

Changes

File	Change
tools/check-doc-truthing.sh	Now the single unified guard: presence invariants (DOC-04/05) + over-claim ratchet (DOC-08/09) + --update.
tools/check-doc-overclaims.sh	Deleted (folded in).
tools/doc-overclaims.allow	Kept (13 sigs unchanged); now owned by the unified script.
.github/workflows/ci.yml	Two Issue #176 build steps → one.
justfile	guard runs the single script; doc-overclaims-bless → doc-truth-bless.
docs/TECH-DEBT.adoc	DOC-16 rewritten to describe the unified guard; DOC-17 marked "folded into DOC-16"; MONITOR note updated.
docs/CAPABILITY-MATRIX.adoc	Change-control points at the single guard.
.machine_readable/6a2/STATE.a2ml	Mirror note records the consolidation.

Verification

$ ./tools/check-doc-truthing.sh
OK: doc-truthing intact — presence invariants + over-claim ratchet (DOC-04/05/08/09).
$ ./tools/check-doc-truthing.sh --update      # baseline regenerates: 13 signatures

• bash -n clean. Both negative directions bite: a new over-claim phrase fails; a dropped banner fails.
• Pure consolidation — no behavioural change to either check, no compiler code touched.
• No active references to the deleted script remain (only intentional historical mentions in the ledger / STATE note / a code comment explaining the merge).

Refs #176
Refs #175

https://claude.ai/code/session_01HR1GHjBfNdfcFZm1XiLXK4

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