chore: move escpod align to rnabioco/eschalign

[jayhesselberth]

escpod align and the escapepod-align crate now live in https://github.com/rnabioco/eschalign as the standalone eschalign binary (history preserved, fresh 0.1.0). This removes them here.

• Removes the crate, escpod align, Stage::Align, the escapepod-align/gpu feature leg, its tests, docs and benchmark.
• escapepod-classify used escapepod_align::fasta::read_fasta; the reader moves to escapepod_signal::fasta (same behaviour, same tests, local FastaError).
• Hard removal, no escpod align stub. The ESCAPEPOD_ALIGN_* switches no longer exist here (eschalign keeps them as deprecated aliases).

Checked on rna: fmt, clippy -D warnings, nextest 932/932, doctests, check --features gpu, --no-default-features --features cli build.