feat: improve session sharing and Kimi transcript support

- normalize Kimi thinking parts and omit empty placeholders
- add standalone session-sharing and UI demo artifacts
- add regression coverage and refresh the Kimi index marker
- bump the Electron app and CLI packages to v0.2.1
- ignore generated app build assets

.gitignore

@@ -9,4 +9,6 @@ release/
 dist/
 app/out/
 HANDOFF.md
-.obelisk/
+.obelisk/
+app/build/
+app/scripts/