perf(cloud): shrink fal cold start by ~20s

[emranemran]

Summary

Three changes to the fal cold-start path, derived from a real cold-start trace in fal.log:

• livepeer_fal_app.py: drop requirements = [...] so fal isolate stops provisioning a separate venv on top of the image's. Combined with the Dockerfile change below, removes the ~10–12s Downloaded transformers / Uninstalled 50 packages / Installed 56 packages block visible on every cold start.
• Dockerfile.cloud: pre-build the venv with uv sync --extra livepeer --extra kafka --no-dev so the runtime uv run --extra livepeer --extra kafka livepeer-runner is a no-op.
• livepeer_fal_app.py dockerfile_str: re-sync after COPY src/ so the daydream-scope editable install is refreshed at image build time (kills the Built daydream-scope @ file:///app rebuild on every cold start).
• livepeer_app.py lifespan: pre-warm the pipeline registry so the torch/diffusers/transformers/torchao import cascade runs at runner startup instead of on the first cloud-proxy call (~8s shifted off the user-perceived connect path).

Combined expected savings: ~20s of user-visible cold start.

Test plan

• uv run ruff check src/scope/cloud/livepeer_app.py src/scope/cloud/livepeer_fal_app.py — clean
• uv run ruff format --check — already formatted
• Both files compile (py_compile)
• fal SDK loads livepeer_fal_app.py and reports requirements = []
• Deploy to scope-livepeer-emran, force a cold start, capture runner logs, compare phase deltas vs the baseline fal.log. The "Downloaded / Uninstalled / Installed" block should be gone, and Registry initialized should fire before the first WS handshake.

🤖 Generated with Claude Code

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[github-actions]

🚀 fal.ai Preview Deployment

Commit	8d78c9d
App ID	daydream/scope-livepeer-pr-1024--preview
WebSocket	wss://fal.run/daydream/scope-livepeer-pr-1024--preview/ws

Testing on Cloud

SCOPE_CLOUD_APP_ID="daydream/scope-livepeer-pr-1024--preview/ws" uv run daydream-scope