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/operator/tls.md

@@ -1,5 +1,7 @@
 # TLS on the Control Plane
 
+> Last reviewed: 2026-05-05
+
 certctl's control plane is HTTPS-only as of v2.2. There is no plaintext `http://` listener, no `auto` mode, no dual-listener bridge, no TLS 1.2 escape hatch. The server refuses to start without a cert+key pair, the agent/CLI/MCP clients reject `http://` URLs at startup, and the Helm chart refuses to render without either an operator-supplied Secret or a cert-manager Certificate CR.
 
 This doc covers four cert provisioning patterns, SIGHUP-based cert rotation, and the client-side CA-trust configuration agents and the CLI need to talk to the server. If you are upgrading from a pre-HTTPS release and want the step-by-step cutover procedure, read [`upgrade-to-tls.md`](upgrade-to-tls.md) first and come back here for reference.