Experimental Astro route caching

<section class="stage"><div class="heading">ROUTE CACHE <span class="hint">miss / hit / invalidate</span></div><div class="cache-flow"><div class="tile request">GET /news</div><div class="arrow">→</div><div class="cache-box">CACHE <b id="cache-state">MISS</b></div><div class="arrow">→</div><div class="tile renderer">RENDER</div></div><div class="caption" id="cache-caption">First request fills the cache</div></section>

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