Add services/wordpress.sh — multi-site WordPress with shared MariaDB

New service: self-hosted WordPress, sized for running several
independent sites the way a hosting company would, not just one blog.

- Multi-site from the start: every site requires a name (no unnamed
  "first instance" special case like mattermost's — there's no
  backward-compat reason to special-case one here) and gets its own
  directory/container/port, but all sites share ONE MariaDB container
  (chain-installed on first site, reused by every other one) instead of
  a dedicated database container per site — same resource-sharing idea
  as services/coturn.sh, just scoped to WordPress's own sites rather
  than shared across different services. Each site gets its own
  database + user within that shared instance.
- E-commerce is just WooCommerce, a normal WordPress plugin — no
  separate infrastructure. PHP memory_limit/upload_max_filesize/
  post_max_size are pre-tuned (256M/64M/64M) so a product-catalog
  import doesn't hit default-image limits on the first try.
- wp-cli (official wordpress:cli image, run as a one-off container
  sharing the site's html volume) does the initial WordPress core
  install non-interactively — title, admin account — so there's no
  browser setup wizard to remember per site. Falls back to printing
  the exact manual command if the site wasn't ready in time.
- Auto-scans for a free host port per site (multiple sites can't all
  bind 8090), matching the "auto-scanned free ports for extras" idea
  already used by mattermost's multi-instance support.
- DB and admin passwords are reused across reruns (checked against the
  DB-password-regeneration bug class already fixed elsewhere in this
  repo, e.g. PR #265) — verified via a real update-mode rerun that the
  credential doesn't change.
- setup.sh: is_installed() gets a wordpress case — every site is named
  from the first one on, so there's never a plain $DOCKER_DIR/wordpress
  directory the default case could match against.
- README.md: added to the utilities services table + copiable list per
  CLAUDE.md's three-step rule for new services. Also fixed `coturn`
  being in the homelab row's prose but missing from the copiable list
  block below it — a pre-existing gap from when coturn.sh was merged.

Verified end-to-end via non-interactive dry runs against a fake docker
shim (no live daemon in this environment): 3 sites installed in
sequence get 3 distinct databases, 3 distinct auto-scanned ports, the
shared DB is only set up once, and an update-mode rerun preserves the
existing DB password rather than regenerating it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TBtExJcqxnokyZZKmphdug

setup.sh

@@ -99,6 +99,10 @@ is_installed() {
         pstn-trunk) [ -f "$DOCKER_DIR/asterisk-digital-ocean/config/asterisk/pstn-trunk-pjsip.conf" ] || [ -f "$DOCKER_DIR/asterisk/config/asterisk/pstn-trunk-pjsip.conf" ] ;;
         sms-inbound) [ -f /opt/sms-inbound/settings.env ] ;;
         ssh-config) false ;;   # repeatable management tool, never shows [installed]
+        # Every WordPress site is named from the first one on (no plain
+        # $DOCKER_DIR/wordpress dir the default case below could match) —
+        # [installed] means "at least one site exists", not any specific one.
+        wordpress) compgen -G "$DOCKER_DIR/wordpress-*" >/dev/null 2>&1 ;;
         *) [ -e "$DOCKER_DIR/$1" ] ;;
     esac
 }