Release v0.3.0: fix binary data corruption, harden PAR2/CRC verificat…

…ion, propagate decompression errors

Breaking changes:
- YencDecoded::verify_crc32() returns Option<bool> (None = no CRC available)
- NntpClient::maybe_decompress() returns Result<Vec<u8>> instead of silently
  falling back to raw data on decompression failure

Bug fixes:
- Binary reader now strips NNTP line terminators before appending to payload
- PAR2 slices with missing IFSC checksums reported as damaged instead of skipped
- PAR2 verification with no IFSC packet and failed MD5 now marks all slices damaged
- ArticleAssembler avoids unnecessary clone for multipart decoded data

Safety hardening:
- 64 MB limit on compressed blocks (prevents OOM)
- PAR2 packet length validation (prevents arithmetic underflow)
- PAR2 zero slice_size rejection (prevents division-by-zero)
- BandwidthLimiter panics on zero rate (prevents division-by-zero)
- LruHeaderCache uses wrapping_add for access counter

See CHANGELOG.md for full details.

Set minimum dependency versions to fix -Z minimal-versions CI

Bump floor versions for all dependencies to prevent resolution to
ancient crates that don't compile on modern stable Rust (e.g.,
flate2 1.0.0 pulling in gcc 0.3.3 with #![feature(convert)]).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Initial release v0.2.0

Async NNTP client library for Rust with TLS, compression, connection
pooling, article parsing, yEnc encoding, NZB parsing, and PAR2
verification. See CHANGELOG.md for details.