v0.7.0

Added

• # record delimiter: DnaSequence::from_str("ACGT#TTGA") (or DnaSequence::join)
  indexes several records (e.g. FASTA entries) as one logical sequence — one SeqId, one
  header, offsets counted across the joined string with each # taking one position. A
  # matches nothing: no hit spans it, SMEM/MEM extension stops at it as at $, and a #
  in a query matches nothing. Leading, trailing and doubled # are rejected.
  alphabet::decode_sequence renders extracted sequences with #.

Changed

• Breaking (run-length files). Run-length format "HRL\x03" / "HRB\x03":
  extraction rows are stored per #-delimited piece. Version 2 files still load; blobs
  written by this version cannot be read by older builds. FORMAT_MAGIC /
  BIDIR_FORMAT_MAGIC now read "HRL\x03" / "HRB\x03".
• Breaking. # is no longer an invalid character: encode_byte(b'#') /
  encode_char('#') return Some(SENTINEL) instead of None, and
  DnaSequence::from_str accepts an interior # (see Added) where it used to return
  InvalidCharacter.

Fixed

• Locate on an index built from DnaSequence::from_encoded bases containing interior
  sentinels: every piece start is now force-sampled, so the LF walk never crosses one.
  Indexes already serialized from such text keep their old samples; rebuild them.