build: move both escapepod pins to v0.27.1

[github-actions]

rust/Cargo.toml and pyproject.toml pin the same upstream, released in
lockstep from rnabioco/escapepod-rs, and leech drives both — signal_refine.py
through the Python binding, refinement.rs through the crate. A skew between
them lets the two prepare backends compute different dwells and different
level-derived features from the same read, which is issue #193: invisible for
four releases, because the arrays keep their shape and look plausible either way.

Opened by .github/workflows/escapepod-sync.yml because the pins disagreed.
Dependabot bumps the tag-pinned crate on its own schedule and has no way to know
a PyPI package in another manifest has to move with it.

uv.lock's escapepod entry is rewritten from PyPI's release record rather than
by uv lock, which re-serializes the whole file (~670 changed lines, ~300
packages gaining emscripten markers) and would bury the one line worth reviewing.

Verify before merging

This moves the pins and re-resolves the locks. It does not check that escapepod
still computes the same thing.

• tests/test_backend_parity.py is the check that matters. It compares
  every array in the npz across both prepare backends, which is exactly the
  divergence this guards against.
• A compile is not enough. cargo check passing says the API still exists,
  not that the values are unchanged.

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