README: reshoot the Plugin Studio at f63d75e — the Explorer-tree rail

readme-shots now clicks the rail's first plugin row (.st-row[role=treeitem],
not a section heading), keeping .vtl-tab as a fallback. Without that, the walk
fell through to the nested gallery's own tabs.

internal/readme-shots.mjs

@@ -280,15 +280,24 @@ await shot('cap5-plugin-studio', '/doxa-maps/plugin-studio/plugin-studio/index.h
   before: async (page) => {
     // The rail lives inside the element's shadow root, so a light-DOM selector finds nothing —
     // click through an evaluated deep walk instead (the same seen-Set walk the readiness guard uses).
+    // The rail is an Explorer tree (f63d75e): its plugin rows are .st-row[role=treeitem], and a
+    // .st-sec row is a section heading, not a plugin. The older .vtl-tab rail is kept as a
+    // fallback. Without a tree row, the walk would reach the NESTED gallery's own .vtl-tab buttons
+    // instead, and click a tab inside the plugin rather than a plugin in the rail.
     await page.evaluate(() => {
-      const seen = new Set(); let first = null
-      ;(function w(n) {
-        if (!n || seen.has(n) || first) return
-        seen.add(n)
-        if (n.tagName === 'BUTTON' && /vtl-tab\b/.test((n.className || '').toString())) { first = n; return }
-        if (n.shadowRoot) w(n.shadowRoot)
-        for (const c of (n.children || [])) w(c)
-      })(document.body)
+      const find = (test) => {
+        const seen = new Set(); let hit = null
+        ;(function w(n) {
+          if (!n || seen.has(n) || hit) return
+          seen.add(n)
+          if (n.nodeType === 1 && test(n)) { hit = n; return }
+          if (n.shadowRoot) w(n.shadowRoot)
+          for (const c of (n.children || [])) w(c)
+        })(document.body)
+        return hit
+      }
+      const first = find((n) => n.matches('.st-row[role="treeitem"]:not(.st-sec)'))
+        || find((n) => n.tagName === 'BUTTON' && /vtl-tab\b/.test((n.className || '').toString()))
       if (first) first.click()
     })
     await page.waitForTimeout(3000)   // let the selected element mount before the main wait