Remove static JSON files and seed step; migrate site settings to Postgres

All content (recipes + imprint/privacy settings) now lives exclusively in
Postgres. The app no longer requires a seed step on first deploy.

Changes:
- helpers.php: load_site_settings() returns defaults when site_settings
  table is empty instead of throwing DatabaseUnavailableException; removes
  legacy JSONB migration path
- data/recipes.json, data/site.json: deleted (content already in DB)
- scripts/db-seed.php: deleted (no longer needed)
- docker-compose.yml: remove RUN_DB_SEED env var and data/ volume mount
- docker/entrypoint.sh: remove RUN_DB_SEED seed block
- docs/COOLIFY.md: update deployment guide to reflect seedless workflow
- .claude/launch.json: add dev server configurations for preview tool

Fresh deploys now start with placeholder legal pages and an empty recipe
list; the admin fills in real content via /admin.php without any CLI step.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

admin.php

@@ -78,10 +78,10 @@ if (!$authed) {
 
 try {
     $allRecipes = load_recipes();
+    $siteSettings = load_site_settings();
 } catch (DatabaseUnavailableException $e) {
     handle_database_unavailable($e);
 }
-$siteSettings = load_site_settings();
 $message = null;
 $errors = [];
 $editing = null;
@@ -186,9 +186,10 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST' && ($_POST['action'] ?? '') === 'save_
             $siteSettings['imprint'] = $imprint;
             $siteSettings['privacy'] = $privacy;
             if (save_site_settings($siteSettings)) {
+                $siteSettings = load_site_settings(true);
                 $message = 'Settings saved.';
             } else {
-                $errors[] = 'Could not save settings. Check permissions on data/site.json.';
+                $errors[] = 'Could not save settings. Check the database connection.';
             }
         }
     }