[Map] Render each UX icon once instead of once per marker

[Kocal]

Q	A
Bug fix?	no
New feature?	no
Deprecations?	no
Documentation?	no
Issues	-
License	MIT

Markers on a map almost always share the same icon, but
AbstractRenderer::getMapAttributes() called UxIconRenderer::render()
for every single marker: a registry lookup, two attribute-validation
passes and an HTML build, repeated identically thousands of times.

Memoise inside UxIconRenderer on the arguments it receives, so the cache
key cannot drift from them and every map of the request shares it. The
generated payload is unchanged.

Rendering a Leaflet map: 1000 markers ~9.7 ms -> ~6.5 ms, 5000 markers
~53 ms -> ~37 ms.

Benchmarked from the repository root with blackfire run symfony php bench.php:

<?php
require __DIR__.'/src/Map/vendor/autoload.php';
require __DIR__.'/src/Map/src/Bridge/Leaflet/vendor/autoload.php';

use Symfony\UX\Icons\Icon as UxIconsIcon;
use Symfony\UX\Icons\IconRegistryInterface;
use Symfony\UX\Icons\IconRenderer;
use Symfony\UX\Map\Bridge\Leaflet\Renderer\LeafletRenderer;
use Symfony\UX\Map\Icon\Icon;
use Symfony\UX\Map\Icon\UxIconRenderer;
use Symfony\UX\Map\Map;
use Symfony\UX\Map\Marker;
use Symfony\UX\Map\Point;
use Symfony\UX\StimulusBundle\Helper\StimulusHelper;

$registry = new class implements IconRegistryInterface {
    public function get(string $name): UxIconsIcon
    {
        return new UxIconsIcon(
            '<path d="M20 10c0 6-8 12-8 12s-8-6-8-12a8 8 0 0 1 16 0Z"/><circle cx="12" cy="10" r="3"/>',
            ['viewBox' => '0 0 24 24', 'fill' => 'none', 'stroke' => 'currentColor', 'stroke-width' => '2'],
        );
    }
};

$renderer = new LeafletRenderer(
    new StimulusHelper(null),
    new UxIconRenderer(new IconRenderer($registry, ['fill' => 'currentColor'])),
);

$map = new Map(center: new Point(48.86, 2.35), zoom: 12);
for ($i = 0; $i < 2000; ++$i) {
    $map->addMarker(new Marker(
        position: new Point(48.86 + $i / 10000, 2.35 + $i / 10000),
        title: 'Marker '.$i,
        icon: Icon::ux('lucide:map-pin'),
    ));
}

$renderer->renderMap($map);

Blackfire:

• before — 182ms wall / 169ms CPU / 8.95MB: https://app.blackfire.io/envs/5f4f9a62-eaa0-45ee-b7b3-a1b879f550e9/profiles/59ffb3aa-97d0-47a7-8f39-8ba8d2f0e807/graph
• after — 79ms wall / 79ms CPU / 8.36MB: https://app.blackfire.io/envs/5f4f9a62-eaa0-45ee-b7b3-a1b879f550e9/profiles/91beef39-f210-460d-b43f-8244a3700e20/graph
• diff: https://app.blackfire.io/envs/5f4f9a62-eaa0-45ee-b7b3-a1b879f550e9/profiles/compare/59ffb3aa-97d0-47a7-8f39-8ba8d2f0e807...91beef39-f210-460d-b43f-8244a3700e20/graph

Analysis, implementation and benchmarks by Claude Opus 5.