feat(webui): add assistant reply fork-from-here

THIRD_PARTY_NOTICES.md

@@ -5,6 +5,37 @@ nanobot Python distribution (`pip install nanobot-ai`).
 
 ---
 
+## Tabler Icons — WebUI fork action icon (MIT)
+
+- **Source**: https://github.com/tabler/tabler-icons
+- **Bundled**: inline SVG path for `arrow-fork` in `nanobot/web/dist/assets/index-*.js`
+
+```
+The MIT License (MIT)
+
+Copyright (c) 2020-2026 Paweł Kuna
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+```
+
+---
+
 ## KaTeX — math rendering (MIT)
 
 - **Source**: https://github.com/KaTeX/KaTeX