docs, comments: the drift the audit listed (audit 2026-10-17, stage 6)

The lines under "Doc and comment drift" that the findings' own commits
did not already fix:
- security.md: a newer confirmation link replaces the older, a reset link
  is not replaced; html/template renders every page (no themes); the
  container keeps eight capabilities, named, not "KILL".
- architecture.md: ImportKey writes over a name's key, as an import must;
  the error text reaches the browser on the Backup page's import refusal.
- guide: with Caddy the key is in Caddy's data, so a full backup refuses
  until certs/ holds a copy (or back up caddy-data).
- comments: sasldb2 holds application passwords in the clear (store,
  app/password.go); texthash folds ASCII (sender.go); the supervisor
  socket's group is supervisor (rpc.go); cert-reload's OpenSSL measurement
  was 3.0.x of bookworm; sendReset's limits (links.go).
Migration 0013's comment stays as shipped.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

build/postfix-cert-reload.sh

@@ -43,7 +43,8 @@ reload() {
 # same_pair says whether a certificate file and a private key file belong
 # together, by comparing the public key each one prints. openssl-x509(1) and
 # openssl-pkey(1) do not say the two print it byte for byte alike; measured
-# in the image, 2026-10-15, OpenSSL 3.0.22: identical for RSA-2048, P-256 and
+# in the image, 2026-10-15, OpenSSL 3.0.x of bookworm, before trixie's 3.5
+# (re-read on 3.5.7 is due with the next look at this script): identical for RSA-2048, P-256 and
 # P-384 keys, and for a P-256 key written in SEC1 form ("EC PRIVATE KEY") -
 # certbot 2.0 and later issue ECDSA keys by default (assumptions C-X1).
 same_pair() {