Expressive forms integrated into Hugo — nav/footer framing (garden#7)

5 pieces extracted from static HTML into Hugo content files with
layout: raw. Each gets the garden nav bar, footer, and garden.css
while preserving custom CSS/JS (Web Audio, SVG, interactive elements).

Now navigable: visitor can browse from homepage to piece and back.
Static copies remain in static/expressive/ as fallback.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

layouts/expressive/raw.html

@@ -0,0 +1,3 @@
+{{ define "main" }}
+{{ .Content }}
+{{ end }}

layouts/expressive/single.html

@@ -0,0 +1,12 @@
+{{ define "main" }}
+<article>
+  <header>
+    <hgroup>
+      <h1>{{ .Title }}</h1>
+      {{ with .Params.form }}<p data-text="dim">{{ . }}</p>{{ end }}
+    </hgroup>
+  </header>
+
+  {{ .Content }}
+</article>
+{{ end }}