Coturn 4.12.0

• Update khash to the latest version
• Update readme to match latest changes
• Add DeepWiki link to the README
• Update docs for drop-invalid-packets and response-origin-only-with-rfc5780
• Multiplexpeer
• examples: exercise uclient thread pools, UDP-GSO, recv_pps in CI tests
• Fix TTL/TOS type conversion
• turnutils_uclient: sender thread pool + UDP-GSO send batching + recv_pps reporting
• Fix memory leak introduced by recvmmsg path
• turnutils_uclient: multi-threaded listener (recv) pool
• examples/turnserver.conf: update description of cli option
• turnutils_uclient: Linux recvmmsg receive path + larger SO_RCVBUF
• Add UDP-GSO send path (--udp-gso)
• turnutils_peer: Linux fast path with drain loop, recvmmsg/sendmmsg, UDP-GSO
• Relay recvmmsg
• fuzzing: use hex escapes for HTTP EOH dictionary entry
• Sync turnserver man page with current CLI options
• Remove stale --ne option from turnserver --help