docs: file R-29 to the register; attach the gate-orphan instance to its class

d4c07873 filed "hostinstall_gates.py is invoked by nothing" as a novel
observation. It is not novel — R-29 already names the class (green gates are
enforced nowhere; one sat RED for 16 releases while every REPORT said green),
and R-29 was missing from OPEN-ITEMS.md entirely, having never been carried
across the 2026-07-27 register rebuild. An open item about work not getting
done was absent from the page that decides what gets done.

Ruling on whether R-29 is the right home for a non-design-v2 gate: YES. Its
title says design-v2, but its own audit list already spans mount-safety,
secrets and dedup gates across four repos, and its part (b) — "the systemic
half is the real item" — is about the enforcement mechanism, which is
gate-agnostic. hub_confirm_gate.py is already on its list and sits in the same
scripts/ directory. No new ID minted; R-29's own text forbids it, and this is
the third re-raise it has absorbed.

- OPEN-ITEMS.md: open R-29 (READY, S(a)/M(b)), with the orphan evidence and
  the two separable parts R-29 already defines.
- OPEN-ITEMS.md: R-94 leg (b) now points at R-29 as its class.
- ROADMAP.md:158: audit list extended with hostinstall_gates.py (RED today,
  1.19.0 != 1.22.0) + hub_confirm_gate.py verified orphan. Entry not rewritten.
- ROADMAP.md:147: cited a non-existent R-164 — it means controller v0.164.0.
- CONTEXT.md:564: asserted in the present tense that the version cross-check is
  "gated by scripts/hostinstall_gates.py". It exists, is red, and runs nowhere.
- OPEN-ITEMS.md: READY #1/#3/#4 markers dropped — they duplicated ranked-list
  positions and the gap was left by the row merged in d4c07873.
- OPEN-ITEMS.md: E-2d citation :322-341 widened to :322-343; the invocation it
  describes is at :343, two lines outside the old range.
- backlog/README.md: two-line lead naming OPEN-ITEMS.md and ROADMAP.md.
- REPORT-record-correction-2026-07-29.md: the report CLAUDE.md:82-87 requires
  for both commits. Root REPORT.md (E-2 increment 1) untouched.

No gate wired, fixed, run or deleted — that is R-29 part (b), its own task.
Documentation only. No version bump, no CHANGELOG entry, no box touched.

documentation/backlog/README.md

@@ -1,6 +1,12 @@
 # documentation/backlog/
 
-Verified-LIVE findings with implementable fix plans that are **not yet implemented**. Preserved here
+**`OPEN-ITEMS.md`** is the register of open work and the file to read first — it holds only what is
+open, one row per item, every row with a state and an owner. **`ROADMAP.md`** is the full history and
+reasoning behind the `R-n` IDs, including shipped and killed items; an ID is minted there, and a new
+instance of an existing item attaches to that ID rather than getting its own.
+
+The rest of this folder: verified-LIVE findings with implementable fix plans that are **not yet
+implemented**. Preserved here
 (instead of on git branches) per the trunk-based, no-branches rule — the fix itself is implemented later
 **directly on `main`**, during a normal/supervised session.