docs: Phase 14 — Last reviewed line sweep across docs/

Per Phase 1 audit at cowork/docs-overhaul-phase-1-audit-2026-05-04/.
Adds a `> Last reviewed: 2026-05-05` line right after the H1 heading
of every doc that didn't already have one (41 files).

This dates the freshness clock for the future Phase 4 per-doc review.
The discipline going forward: when a doc's content gets a meaningful
edit, bump the date. When the date gets old (e.g., >6 months), the
doc earns a freshness-review pass.

Mechanical insertion via awk one-liner, applied to every docs/*.md
that didn't already match `grep -q 'Last reviewed:'`. Files that
already carried the line from earlier Phase 2 work (the navigation
index, the new connector docs, the new SCEP server / legacy-clients-
TLS-1.2 / release-verification docs, and the 5 per-connector deep
dives) were skipped to avoid duplicate insertion.

Net: every doc in docs/ now has a Last reviewed line.

docs/archive/upgrades/to-v2-jwt-removal.md

@@ -1,5 +1,7 @@
 # Upgrading past G-1 — `CERTCTL_AUTH_TYPE=jwt` removal
 
+> Last reviewed: 2026-05-05
+
 > **Archived 2026-05-05.** This upgrade guide applies to operators
 > upgrading past the G-1 milestone (the `CERTCTL_AUTH_TYPE=jwt` removal).
 > Current operators on post-G-1 releases don't need this. For the