fix(production): fix multiple remote server errors from nginx logs

- Fix 413 Request Entity Too Large: bump client_max_body_size to 256M,
  PHP post_max_size/upload_max_filesize to 256M, fastcgi timeouts to 300s
- Fix missing v_smtp_active view: add IF NOT EXISTS to all CREATE VIEW
  statements in schema.sql for idempotent migrates
- Fix bars.svg 404: create animated SVG spinner in app/public/assets/img/
- Fix nginx rate limiting: increase admin zone from 60r/m (1 r/s) to
  300r/m (5 r/s) with burst=30 to handle ~11 concurrent HTMX fragment
  GETs on contenus.php page load
- Add deploy-nginx recipe to justfile for uploading nginx config to server
- Database readonly issue mitigated by existing --chown + deploy-server.sh
  permissions fix
- Add comprehensive PHP/JS debugging logs for settings checkboxes:
  per-field raw POST values in error_log, console.log on htmx:beforeSend,
  htmx:sendError, htmx:afterRequest, toast lifecycle
- Fix toast auto-remove script: use getElementById with unique ID instead
  of querySelector which could remove wrong toast on rapid clicks

app/public/assets/img/bars.svg

@@ -0,0 +1,11 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="currentColor">
+  <rect x="1" y="1" width="6" height="22" rx="1">
+    <animate attributeName="opacity" values="0.3;1;0.3" dur="1s" repeatCount="indefinite" begin="0s"/>
+  </rect>
+  <rect x="9" y="1" width="6" height="22" rx="1">
+    <animate attributeName="opacity" values="0.3;1;0.3" dur="1s" repeatCount="indefinite" begin="0.2s"/>
+  </rect>
+  <rect x="17" y="1" width="6" height="22" rx="1">
+    <animate attributeName="opacity" values="0.3;1;0.3" dur="1s" repeatCount="indefinite" begin="0.4s"/>
+  </rect>
+</svg>