v0.3.0

First public release of mdnspp as a standalone C++23 mDNS/DNS-SD library.

Highlights

Standalone implementation -- no external dependencies for the default policy; the original mdns C-library dependency has been removed entirely
Policy-based architecture -- swap socket, timer, and executor implementations at compile time (DefaultPolicy for native sockets, AsioPolicy for ASIO completion token support, MockPolicy for testing)
ASIO completion tokens -- callbacks, futures, coroutines (use_awaitable), and deferred operations
Cross-platform -- Linux, macOS, and Windows with CI coverage across GCC 13/14, Clang 18/19, MSVC 17+, and Xcode 15.4+
QU bit support (RFC 6762 section 5.4) -- queriers and service discovery can request unicast responses by setting unicast = true on async_query, async_discover, and async_browse; service servers detect the QU bit and route responses accordingly

observer -- passively listen to all mDNS multicast traffic
querier -- send mDNS queries and collec2t matching records with a configurable silence timeout
service_discovery -- discover services by type (async_discover for raw records, async_browse for aggregated resolved_service values)
service_server -- announce a service and respond to matching queries with RFC 6762-compliant random delay

Minimum Clang version bumped from 17 to 18+ due to template deduction failures in Clang 17's <tuple> implementation when used with templated operator<< overloads
operator<< overloads for record types, endpoint, dns_type, and dns_class are now function templates (std::basic_ostream<CharT, Traits>&) instead of inline functions taking std::ostream&; public headers use <iosfwd> instead of <ostream>
The move_only_function fallback (for compilers without std::move_only_function) is now a proper type-erased wrapper instead of an alias for std::function