garden: sessions redundancy + theme toggle + no toggle reveal

- Sessions list: no tag header, stripped 'Vigo Session Log:' prefix
- Session single: flat sections instead of fragment toggle (details/summary)
- Theme toggle: explicit font-family + color ensures emoji icon renders
- New: layouts/sessions/list.html, sessions/single.html
- Changed: content/sessions/*.md (no fragment shortcodes), garden.css

public/css/garden.css

@@ -58,10 +58,50 @@ body {
   font-family: var(--garden-font);
 }
 
-/* ── Layout — ASW handles body > main container now ────────── */
-/* Override --width-lg for narrower garden feel */
-:root {
-  --width-lg: 900px;
+/* ── Layout — narrow container for garden prose feel ────────── */
+/* Override ASW's responsive max-width cascade. ASW goes up to 1450px
+   on wide screens — too much for a garden of text. We cap at 720px for
+   prose pages, 900px for data-heavy pages (estate, sessions). */
+@media (min-width: 576px) {
+  body > main:not([data-layout="fluid"]),
+  body > nav,
+  body > footer {
+    max-width: 510px;
+  }
+}
+@media (min-width: 768px) {
+  body > main:not([data-layout="fluid"]),
+  body > nav,
+  body > footer {
+    max-width: 660px;
+  }
+}
+@media (min-width: 1024px) {
+  body > main:not([data-layout="fluid"]),
+  body > nav,
+  body > footer {
+    max-width: 720px;
+  }
+}
+@media (min-width: 1280px) {
+  body > main:not([data-layout="fluid"]),
+  body > nav,
+  body > footer {
+    max-width: 720px;
+  }
+}
+@media (min-width: 1536px) {
+  body > main:not([data-layout="fluid"]),
+  body > nav,
+  body > footer {
+    max-width: 720px;
+  }
+}
+
+/* Estate and sessions pages are data-heavy — give them more room */
+body > main[data-page="estate"],
+body > main[data-page="sessions"] {
+  max-width: 900px !important;
 }
 
 /* ── Links — violet accent, indigo hover ──────────────────── */
@@ -114,6 +154,20 @@ pre {
 }
 
 
+/* ── Theme toggle ───────────────────────────────────── */
+/* Ensure the emoji icon is always visible — override
+   garden's monospace font-family which may lack emoji glyphs */
+body > nav [data-theme-toggle] {
+  font-family: system-ui, -apple-system, sans-serif;
+  font-size: 1.35rem;
+  color: var(--garden-text);
+  opacity: 0.85;
+  transition: opacity 0.2s;
+}
+body > nav [data-theme-toggle]:hover {
+  opacity: 1;
+}
+
 /* ── Session fragments — expandable doors (from context.html) ── */
 [data-type="dialogue"]  { --fragment-color: var(--garden-dialogue); }
 [data-type="fix"]       { --fragment-color: var(--garden-fix); }