Add compose-based preview stack for the reasoning dashboard

[pankaj4u4m]

Summary

The preview panel had nothing to work with: this repo had no shipit.yaml and no compose file at all, so ShipIt fell through to its onboarding UI. Adding a compose: key alone was not possible — there was no compose file to point at — so this change creates both, wired to the one genuinely previewable surface in the repo: the Vite + React reasoning dashboard.

Rationale

Preview = the frontend dashboard, on 3125. It mirrors the native make start stack (lemoncrow stack start), keeping the ports the project already uses (frontend 3125, api 8787) rather than the generic Vite/FastAPI defaults, so the preview matches local dev and VITE_API_URL conventions.

The api service is manual, not auto. lemoncrow.core.service.api imports lemoncrow.pro, a private subpackage referenced 327 times across src/ that is absent from this checkout and is not a submodule. The service therefore cannot boot from the open-source repo — verified: it exits 1 on ModuleNotFoundError: No module named 'lemoncrow.pro'. Marking it auto would put a crash-looping container behind the preview pane. As manual it stays a one-command opt-in (shipit service start api) that works as-is in a checkout that has src/lemoncrow/pro. depends_on: api is deliberately omitted so the preview doesn't drag the manual service up with it.

Python deps install in the service, not agent.install. A virtualenv is pinned to the interpreter that created it, and the python:3.13 service's interpreter is not the agent container's. Both venvs are placed outside the mounted workspace (/tmp/uvenv, /tmp/venv) specifically so the service can never clobber the agent's own ./.venv, which uv run depends on per CLAUDE.md. uv sync --frozen honours uv.lock and never rewrites it, keeping the working tree clean.

uv sync --no-install-project + PYTHONPATH=/app/src rather than an editable install. This is forced by a pre-existing repo bug (below), but it is also the better preview shape: source edits are live with no reinstall step.

Two pre-existing repo bugs found while verifying (not fixed here)

Both are independent of this change and affect anyone building or running the project:

1. pyproject.toml force-includes a file that does not exist. [tool.hatch.build.targets.wheel.force-include] names src/lemoncrow/pro/capabilities/code_context/explore_reranker_model.json, which has never been committed (absent from HEAD). Every wheel and editable build fails with FileNotFoundError: Forced include not found. This breaks uv run in the agent container too, so CLAUDE.md's documented uv run pytest / uv run mypy workflow does not currently work from a clean checkout.
2. lemoncrow.pro is missing but hard-imported. src/lemoncrow/core/capabilities/host_router_bridge.py:10 imports it unguarded, making the FastAPI service unimportable in this repo.

Changes

• shipit.yaml (new) — declares compose: docker-compose.yml, which is what enables the preview panel. agent.install runs npm ci --prefix frontend because frontend/node_modules is absent from a fresh checkout and the dev server needs it. Explicit install-inputs re-enables the content-keyed install skip (the --prefix form isn't auto-recognised), and dep-dirs points the overlay store at frontend/node_modules.
• docker-compose.yml (new) — frontend (node:20-slim, auto, gated on install) and api (python:3.13, manual, self-installing venv), with LEMONCROW_REQUIRE_AUTH: "0" so the non-loopback bind doesn't 503 every protected route in the sandbox, and LEMONCROW_ROOT/HOME pointed at /tmp to keep the SQLite store and caches out of the git tree.
• frontend/vite.config.ts — added server.watch polling, opt-in via VITE_USE_POLLING (set only in compose). Required because inotify events don't cross the agent/service mount-namespace boundary, so hot reload would silently no-op on agent edits; gating it keeps the cheaper default watcher for native npm run dev.

Test plan

Verified in this session:

• shipit service list reconciles to frontend running auto 3125 / api stopped manual 8787.
• Dashboard loads in the browser at :3125 — nav, stat tiles, and window selector render, degrading gracefully to "Daemon unreachable" with the api service stopped (expected without lemoncrow.pro).
• Hot reload confirmed end-to-end: editing frontend/src/pages/Overview.tsx from the agent container produced [vite] hmr update /src/pages/Overview.tsx in the service log. The probe edit was reverted (git diff clean).
• npm --prefix frontend run typecheck passes with the vite.config.ts change.
• api failure mode confirmed by reading its logs, not assumed.

To check the full stack in a checkout that has src/lemoncrow/pro: shipit service start api, then confirm the "Daemon unreachable" chip turns healthy and the stat tiles populate.