feat: rewrite ScriptLibraryPage with Browse/Configure pane modes

- Add paneMode state ('browse' | 'configure') local to page
- Move ScriptFilterBar inside left pane column (hidden in configure mode)
- inputValue owned at page level to survive mode transitions
- Left pane: ScriptFilterBar + ScriptTemplateList in browse; ScriptConfigurePane in configure
- Right pane: ScriptPreview only (read-only); empty state when no template selected
- canGenerate derived from usePermissions().isEngineer (matching ScriptGeneratorPanel pattern)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/ScriptLibraryPage.tsx

@@ -1,19 +1,28 @@
 import { useState, useEffect } from 'react'
+import { Terminal } from 'lucide-react'
 import { useScriptGeneratorStore } from '@/store/scriptGeneratorStore'
+import { usePermissions } from '@/hooks/usePermissions'
 import { ScriptFilterBar } from '@/components/scripts/ScriptFilterBar'
 import { ScriptTemplateList } from '@/components/scripts/ScriptTemplateList'
-import { ScriptGeneratorPanel } from '@/components/scripts/ScriptGeneratorPanel'
+import { ScriptConfigurePane } from '@/components/scripts/ScriptConfigurePane'
+import { ScriptPreview } from '@/components/scripts/ScriptPreview'
 
 export default function ScriptLibraryPage() {
-  // inputValue is owned here so ScriptFilterBar and ScriptTemplateList
-  // can coordinate clear-search without direct coupling.
+  const [paneMode, setPaneMode] = useState<'browse' | 'configure'>('browse')
+  // inputValue owned here so it survives Configure ↔ Browse transitions
   const [inputValue, setInputValue] = useState('')
+
   const loadCategories = useScriptGeneratorStore(s => s.loadCategories)
   const loadTemplates = useScriptGeneratorStore(s => s.loadTemplates)
   const setSearch = useScriptGeneratorStore(s => s.setSearch)
+  const selectTemplate = useScriptGeneratorStore(s => s.selectTemplate)
+  const clearOutput = useScriptGeneratorStore(s => s.clearOutput)
+  const selectedTemplate = useScriptGeneratorStore(s => s.selectedTemplate)
+
+  const { isEngineer } = usePermissions()
+  const canGenerate = isEngineer
 
   useEffect(() => {
-    // loadCategories must complete before loadTemplates can resolve slugs
     loadCategories().then(() => loadTemplates())
   }, [loadCategories, loadTemplates])
 
@@ -22,6 +31,16 @@ export default function ScriptLibraryPage() {
     setSearch('')
   }
 
+  const onConfigure = (id: string) => {
+    selectTemplate(id)
+    setPaneMode('configure')
+  }
+
+  const onBack = () => {
+    clearOutput()
+    setPaneMode('browse')
+  }
+
   return (
     <div className="flex flex-col gap-4 p-6 h-full">
       {/* Page header */}
@@ -32,18 +51,37 @@ export default function ScriptLibraryPage() {
         </p>
       </div>
 
-      {/* Filter bar */}
-      <ScriptFilterBar inputValue={inputValue} setInputValue={setInputValue} />
-
       {/* Two-column layout */}
       <div className="grid grid-cols-[320px_1fr] gap-4 flex-1 min-h-0">
-        {/* Template list — scrollable */}
-        <div className="glass-card-static overflow-y-auto">
-          <ScriptTemplateList inputValue={inputValue} onClearSearch={onClearSearch} />
-        </div>
+        {/* Left pane — Browse or Configure mode */}
+        {paneMode === 'browse' ? (
+          <div className="glass-card-static flex flex-col overflow-hidden">
+            <div className="p-2 pb-0">
+              <ScriptFilterBar inputValue={inputValue} setInputValue={setInputValue} />
+            </div>
+            <div className="flex-1 overflow-y-auto">
+              <ScriptTemplateList
+                inputValue={inputValue}
+                onClearSearch={onClearSearch}
+                onConfigure={onConfigure}
+              />
+            </div>
+          </div>
+        ) : (
+          <ScriptConfigurePane canGenerate={canGenerate} onBack={onBack} />
+        )}
 
-        {/* Generator panel */}
-        <ScriptGeneratorPanel />
+        {/* Right pane — read-only ScriptPreview */}
+        {selectedTemplate === null ? (
+          <div className="glass-card-static h-full flex flex-col items-center justify-center gap-3 text-center p-8">
+            <Terminal size={40} className="text-muted-foreground/40" />
+            <p className="text-sm text-muted-foreground">Select a template to get started</p>
+          </div>
+        ) : (
+          <div className="glass-card-static h-full overflow-hidden p-4">
+            <ScriptPreview />
+          </div>
+        )}
       </div>
     </div>
   )