feat(custom-css-manager): implementar TIPO 3 - CSS Crítico Personalizado

Nuevo sistema de gestión de CSS personalizado con panel admin:
- Admin/CustomCSSManager: CRUD de snippets CSS (crítico/diferido)
- Public/CustomCSSManager: Inyección dinámica en frontend
- Schema JSON para configuración del componente

Migración de CSS estático a BD:
- Tablas APU (~14KB) → snippet diferido en BD
- Tablas Genéricas (~10KB) → snippet diferido en BD
- Comentadas funciones legacy en enqueue-scripts.php

Limpieza de archivos obsoletos:
- Eliminado build-bootstrap-subset.js
- Eliminado migrate-legacy-options.php
- Eliminado minify-css.php
- Eliminado purgecss.config.js

Beneficios:
- CSS editable desde admin sin tocar código
- Soporte crítico (head) y diferido (footer)
- Filtrado por scope (all/home/single/archive)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

minify-css.php

@@ -1,60 +0,0 @@
-<?php
-/**
- * Simple CSS Minifier Script
- * Run from command line: php minify-css.php
- */
-
-function minify_css($css) {
-    // Remove comments
-    $css = preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $css);
-
-    // Remove space after colons
-    $css = str_replace(': ', ':', $css);
-
-    // Remove whitespace
-    $css = str_replace(array("\r\n", "\r", "\n", "\t", '  ', '    ', '    '), '', $css);
-
-    // Remove space before and after specific characters
-    $css = preg_replace('/\s*([{};,>+~])\s*/', '$1', $css);
-
-    // Remove last semicolon before closing brace
-    $css = str_replace(';}', '}', $css);
-
-    // Trim
-    $css = trim($css);
-
-    return $css;
-}
-
-$files = [
-    'Assets/Css/css-global-accessibility.css' => 'Assets/Css/css-global-accessibility.min.css',
-    'Assets/Css/style.css' => 'Assets/Css/style.min.css',
-];
-
-$base_path = __DIR__ . '/';
-
-foreach ($files as $source => $dest) {
-    $source_path = $base_path . $source;
-    $dest_path = $base_path . $dest;
-
-    if (file_exists($source_path)) {
-        $css = file_get_contents($source_path);
-        $minified = minify_css($css);
-
-        file_put_contents($dest_path, $minified);
-
-        $original_size = strlen($css);
-        $minified_size = strlen($minified);
-        $savings = $original_size - $minified_size;
-        $percent = round(($savings / $original_size) * 100, 1);
-
-        echo "Minified: $source\n";
-        echo "  Original: " . number_format($original_size) . " bytes\n";
-        echo "  Minified: " . number_format($minified_size) . " bytes\n";
-        echo "  Savings: " . number_format($savings) . " bytes ($percent%)\n\n";
-    } else {
-        echo "File not found: $source\n";
-    }
-}
-
-echo "Done!\n";