Move install path to /opt/theta42/proxy, secrets to /etc/proxy/secrets.js

- ops/install.sh now installs to /opt/theta42/proxy (was /var/www/proxy)
  and seeds /etc/proxy/secrets.js from secrets.js.example on first run
  (never overwritten on later runs), instead of requiring a manual
  nodejs/conf/secrets.js edit inside the repo checkout.
- ops/proxy.service points at the new install path and sets
  CONF_SECRETS=/etc/proxy/secrets.js (requires @simpleworkjs/conf >=
  1.2.0, already the pinned version) so the app picks up the secrets
  file with no symlink into the repo checkout.
- install.sh now prints the version it's updating from/to (or "Already
  up to date") on every run, instead of a silent update.
- Updated README/DEPLOYMENT/installation docs to match the new paths.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

ops/proxy.service

@@ -8,9 +8,10 @@ Type=simple
 Restart=always
 RestartSec=1
 User=root
-WorkingDirectory=/var/www/proxy/nodejs
+WorkingDirectory=/opt/theta42/proxy/nodejs
 Environment="NODE_ENV=production"
-ExecStart=/usr/bin/env node /var/www/proxy/nodejs/bin/www
+Environment="CONF_SECRETS=/etc/proxy/secrets.js"
+ExecStart=/usr/bin/env node /opt/theta42/proxy/nodejs/bin/www
 
 [Install]
 WantedBy=multi-user.target