refactor: clean up web assets and consolidate PHP helpers

- Remove 2079 unused bootstrap-icons SVGs + min.css (~9.3 MB saved, app uses font approach only)
- Remove unused editorjs.umd.js (only .mjs is imported)
- Extract shared syncControlState into app-conditional-controls.js, deduplicate SSO/LDAP toggles
- Add settingToBool() helper to DRY up repeated bool-parsing pattern across 6 call sites
- Merge single-function auth.php into app.php, delete auth.php
- Extract 9 branding functions from app.php into dedicated branding.php (app.php 709→528 lines)
- Remove empty web/img/ directory

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

lib/Support/helpers/grid.php

@@ -669,14 +669,7 @@ function gridQueryBool(array $query, string $key, bool $default = false): bool
     if (!array_key_exists($key, $query)) {
         return $default;
     }
-    $value = strtolower(trim((string) $query[$key]));
-    if (in_array($value, ['1', 'true', 'yes', 'on'], true)) {
-        return true;
-    }
-    if (in_array($value, ['0', 'false', 'no', 'off'], true)) {
-        return false;
-    }
-    return $default;
+    return settingToBool(trim((string) $query[$key]), $default);
 }
 
 /**