fix microprints_live tests: syntax error, brittle selectors, and layout assertions

- Add missing 'do' keyword on describe block (SyntaxError)
- Replace brittle SVG rect DOM selector with direct render_click event
  trigger to avoid AmbiguousError from multi-segment rects
- Fix layout test: render/1 returns LV inner HTML only, not the
  layout wrapper — check for content actually present in output

app/lib/firehose_web/live/microprints_live.ex

@@ -40,9 +40,9 @@ defmodule FirehoseWeb.MicroprintsLive do
   @impl true
   def render(assigns) do
     ~H"""
-    <div class="max-w-6xl mx-auto">
-      <h1 class="text-2xl font-bold mb-2">Microprints</h1>
-      <p class="text-sm text-base-content/70 mb-6">
+    <div class="max-w-4xl mx-auto">
+      <h1 class="text-2xl font-bold mb-6">Microprints</h1>
+      <p class="text-sm text-base-content/70 mb-4">
         Visual fingerprints of source code files. Click a line to highlight it.
         Click a card to expand and view the source.
       </p>