[safina57]

Adds a Playwright e2e suite covering the desktop (1440x900 Chrome) and mobile (Pixel 7) layouts.

What it covers

• Both layouts: first visit through consent, language and every tour step, with the workspace handed back and nothing shown again after a reload; theme persistence; switching to French and back; the terms and 404 pages.
• Desktop: a chat turn with citation pills, contact links, map pins and follow-up chips; map pin to trial list to summary; trials added to the chat ride along with every message and show under it until removed; saving a trial, starting a new conversation and reopening it from saved trials; PDF export; the contact dialog.
• Mobile: opening on the map, the search bar opening the chat, a citation collapsing the chat onto its card, the details drawer, asking about a trial from the drawer, saving from the drawer, and the map controls clearing the search bar.

How it runs

• /chat/stream is answered with a canned reply built from real trials fetched from /debug/trials; every other call hits the live backend. Runs are deterministic and spend no LLM tokens, and no API key is needed.
• e2e/live.spec.ts exercises the real agent and only runs with E2E_LIVE=1 (paid tokens).
• Needs a running non-production backend on a populated database. pnpm e2e starts Vite if it is not up; E2E_API_URL points at the backend (default http://localhost:8000). Install the browser once per machine with pnpm exec playwright install chromium.
• Vitest is limited to src/**/*.test.* so it no longer picks up the specs; Playwright output folders are git-ignored.

Not wired into CI or pre-commit: it needs a seeded database and live servers, so it is a manual check before merging to staging.

Some specs assert behaviour fixed in #152 (context pills under the user message, the mobile map overlay placement), so merge #152 first.