This PR adds native MPRIS2 support to ncmpcpp, so it can be controlled directly via D-Bus clients such as playerctl and consumed by status bars like Waybar without external bridges.

What’s included:

• New optional MPRIS D-Bus module:
  • src/mpris_dbus.cpp
  • src/mpris_dbus.h
• Build integration:
  • configure.ac: adds --enable-dbus-mpris and dbus-1 detection
  • src/Makefile.am: adds new source/header
• Runtime integration in main loop:
  • initialize/shutdown MPRIS
  • process D-Bus events in the main loop
  • register D-Bus fd callback on footer window

Implemented interfaces:

• org.mpris.MediaPlayer2
• org.mpris.MediaPlayer2.Player
• org.freedesktop.DBus.Properties
• org.freedesktop.DBus.Introspectable

Implemented properties/methods/signals:

• Properties: Get, GetAll, Set
• Player methods: Play, Pause, PlayPause, Stop, Next, Previous, Seek, SetPosition, OpenUri
• Signals: PropertiesChanged, Seeked
• Player properties include:
  • PlaybackStatus, Metadata, Position
  • LoopStatus, Shuffle, Volume, Rate, MinimumRate, MaximumRate
  • CanGoNext, CanGoPrevious, CanPlay, CanPause, CanSeek, CanControl
• MediaPlayer2 properties include:
  • Identity, DesktopEntry
  • SupportedUriSchemes, SupportedMimeTypes
  • CanQuit, CanRaise, CanSetFullscreen, Fullscreen, HasTrackList

Behavior notes:

• Rate is exposed for MPRIS compatibility; only 1.0 is accepted.
• HasTrackList is false (TrackList interface is not implemented).
• Metadata includes standard fields like mpris:trackid, mpris:length, xesam:title, xesam:artist, xesam:album, xesam:url.

Why?
This enables first-class interoperability with the Linux media ecosystem (playerctl, Waybar, other MPRIS consumers) directly from ncmpcpp, without requiring separate MPD MPRIS bridge processes.

Build instructions:

• Regenerate autotools files:
  autoreconf -fi
• Configure with native MPRIS enabled:
  ./configure --enable-dbus-mpris
• Build:
  make -j"$(nproc)"
• Optional install:
  sudo make install
• Run:
  ./src/ncmpcpp

Dependencies

• dbus-1 (required when --enable-dbus-mpris is used)
• regular ncmpcpp deps (libmpdclient, ncursesw, boost, etc.)

Quick runtime check
playerctl -l
playerctl -p ncmpcpp status

Manual testing:

• playerctl -l shows ncmpcpp
• playerctl -p ncmpcpp status
• playerctl -p ncmpcpp play-pause
• playerctl -p ncmpcpp next
• playerctl -p ncmpcpp previous
• playerctl -p ncmpcpp metadata
• Waybar mpris module displays and updates state/track info without UnknownProperty errors.