docs: add workflow migration plan and checkpoint current state

frontend/src/pages/Admin.tsx

@@ -1706,7 +1706,11 @@ function AssetLibraryPanel() {
   })
 
   const createMut = useMutation({
-    mutationFn: () => createAssetLibrary({ name: newName, description: newDesc || undefined, blend_file: newFile! }),
+    mutationFn: () => createAssetLibrary({
+      name: newName.trim(),
+      description: newDesc.trim() || undefined,
+      blend_file: newFile!,
+    }),
     onSuccess: () => {
       toast.success('Asset library created')
       qc.invalidateQueries({ queryKey: ['asset-libraries'] })
@@ -1760,32 +1764,33 @@ function AssetLibraryPanel() {
         <div className="p-4 border-b border-border-light bg-surface-alt space-y-3">
           <div className="flex gap-3">
             <input
-              className="input flex-1"
+              className="input-base flex-1"
               placeholder="Library name"
               value={newName}
               onChange={(e) => setNewName(e.target.value)}
             />
             <input
-              className="input flex-1"
+              className="input-base flex-1"
               placeholder="Description (optional)"
               value={newDesc}
               onChange={(e) => setNewDesc(e.target.value)}
             />
           </div>
-          <div className="flex items-center gap-3">
-            <label className="btn-secondary cursor-pointer">
-              <Upload size={14} />
-              {newFile ? newFile.name : 'Choose .blend file'}
-              <input
-                type="file"
-                accept=".blend"
-                className="hidden"
-                onChange={(e) => setNewFile(e.target.files?.[0] ?? null)}
-              />
-            </label>
+          <div className="flex items-center gap-3 flex-wrap">
+            <input
+              type="file"
+              accept=".blend,application/octet-stream"
+              className="input-base min-w-[18rem] flex-1 file:mr-3 file:rounded-md file:border-0 file:bg-accent file:px-3 file:py-1.5 file:text-sm file:font-medium file:text-accent-text hover:file:bg-accent-hover"
+              onChange={(e) => setNewFile(e.target.files?.[0] ?? null)}
+            />
+            {newFile && (
+              <span className="text-xs text-content-muted font-mono">
+                {newFile.name}
+              </span>
+            )}
             <button
               className="btn-primary"
-              disabled={!newName || !newFile || createMut.isPending}
+              disabled={!newName.trim() || !newFile || createMut.isPending}
               onClick={() => createMut.mutate()}
             >
               {createMut.isPending ? 'Creating...' : 'Create'}