fix(e2e): restore playwright install in install-python

Playwright here backs Python embeddings (prompt_client), not frontend
e2e. The Cypress migration replaced frontend e2e but this line was
removed by mistake, breaking `make install-python`. Restore it per
reviewer feedback on #774.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: PRAteek-singHWY

Makefile

@@ -75,8 +75,9 @@ install-deps: install-deps-python install-deps-typescript
 install-python:
 	virtualenv -p python3  venv
 	. ./venv/bin/activate &&\
-	make install-deps-python
-	
+	make install-deps-python &&\
+	playwright install
+
 install-typescript:
 	yarn add webpack && cd application/frontend && yarn build