Projekt-Settings-Dialog + Library Phase A + Material-Merger

- Project-Settings-Dialog (Voreinstellungen Geschoss/Schnitt + Material-Editor)
  ueber Zahnrad-Icon in Oberleiste; Defaults werden in schnitte.pick_schnitt
  + GeschossManager als Vorgabe genommen, pro-Element-Werte unangetastet
- Dossier-Library Phase A (lokal, read-only): rhino/library.py + LibraryBrowser
  Satellite; Seed-Manifest unter ~/Library/Application Support/Dossier/library/
- Material-Merger: _get_all_materials(doc) merged builtin _MATERIAL_LIBRARY
  mit Projekt-Settings-Materialien (inkl. Library-Imports); Wand-Erstellung,
  Sub-Layer-Anlage + Elemente-Material-Dropdown ziehen jetzt aus dem Merge

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/LibraryApp.jsx

@@ -0,0 +1,32 @@
+import { useState, useEffect } from 'react'
+import LibraryBrowser from './components/LibraryBrowser'
+import { notifyReady, onMessage, send } from './lib/rhinoBridge'
+
+export default function LibraryApp() {
+  const [manifest,    setManifest]    = useState({ items: [] })
+  const [importedIds, setImportedIds] = useState([])
+  const [libraryRoot, setLibraryRoot] = useState('')
+
+  useEffect(() => {
+    onMessage('LIBRARY_STATE', ({ manifest, importedIds, libraryRoot }) => {
+      if (manifest)    setManifest(manifest)
+      if (importedIds) setImportedIds(importedIds)
+      if (libraryRoot) setLibraryRoot(libraryRoot)
+    })
+    notifyReady()
+    const blockContext = (ev) => ev.preventDefault()
+    document.addEventListener('contextmenu', blockContext)
+    return () => document.removeEventListener('contextmenu', blockContext)
+  }, [])
+
+  return (
+    <LibraryBrowser
+      manifest={manifest}
+      importedIds={importedIds}
+      libraryRoot={libraryRoot}
+      onImport={(id) => send('IMPORT_ITEM', { id })}
+      onReload={() => send('RELOAD', {})}
+      onClose={() => send('CLOSE', {})}
+    />
+  )
+}