feat: discord presence, cached audio playback, multiinstance safety

Add
- Discord rich presence ("Listening to", cover, progress, Listen Along
  button). enable via [discord] client_id in config.toml : retries quietly
  if Discord isn't running. new dep: discord-rich-presence.
- :save! / :w! to overwrite a playlist. Plain :save now refuses to
  clobber an existing name.

Change
- Download audio with yt-dlp into the cache dir and play the local file
  (mpv --ytdl=no) instead of streaming. Keep the last 40 files and
  prefetch the next queued track.
- show the the actual yt-dlp/mpv error on playback failure instead of the
  generic "update yt-dlp" hint; allow wider status messages (70 - 120 char).
- Split artists from YouTube's linked artist runs and yt-dlp's 'artists'
  list (new Track::artists) rather than guessing from the display string.
  Fallback splitter keeps names like "Tyler, The Creator" whole and
  matches separators case-insensitively. (shit)
- Restyle selection (accent bold text + bar) and tab bar (underlined
  active tab instead of pills)
- Share one ureq agent across yt Music requests

Fix
- Multiple drift instances: only the first (flock on session.lock) owns
  the session, and playlist saves merge with what other instances wrote.
- Collection picker no longer steals keys while typing.
- "Play next" now shifts `played` indices so shuffle history stays right.
- Leaving the queue for a playlist/result list marks the queue as done.
- Replace unwrap() in lyrics sorting with total_cmp (NaN-safe).

install.sh

@@ -1,17 +1,76 @@
 #!/bin/sh
-set -e
+set -eu
+
+install_packages() {
+    if [ "$(id -u)" -eq 0 ]; then
+        "$@"
+    else
+        sudo "$@"
+    fi
+}
+
+echo "-> Detecting package manager..."
+
+if command -v pacman >/dev/null 2>&1; then
+    # Arch Linux, Manjaro, EndeavourOS, CachyOS
+    install_packages pacman -S --needed --noconfirm \
+        mpv yt-dlp base-devel rust
+
+elif command -v apt-get >/dev/null 2>&1; then
+    # Debian, Ubuntu, Linux Mint, Pop!_OS, elementary OS
+    install_packages apt-get update
+    install_packages apt-get install -y \
+        mpv yt-dlp build-essential cargo
+
+elif command -v dnf >/dev/null 2>&1; then
+    # Fedora, RHEL (ew), Rocky Linux, AlmaLinux
+    install_packages dnf install -y \
+        mpv yt-dlp gcc gcc-c++ make cargo
+
+elif command -v zypper >/dev/null 2>&1; then
+    # openSUSE Leap, Tumbleweed, SUSE Linux Enterprise
+    install_packages zypper --non-interactive install \
+        mpv yt-dlp gcc gcc-c++ make cargo
+
+elif command -v xbps-install >/dev/null 2>&1; then
+    # Void Linux
+    install_packages xbps-install -Sy \
+        mpv yt-dlp base-devel cargo
+
+elif command -v apk >/dev/null 2>&1; then
+    # Alpine Linux or Chimera
+    install_packages apk add \
+        mpv yt-dlp build-base cargo
+
+elif command -v emerge >/dev/null 2>&1; then
+    # Gentoo :3
+    install_packages emerge \
+        media-video/mpv net-misc/yt-dlp \
+        sys-devel/gcc dev-lang/rust
+
+elif command -v zypper >/dev/null 2>&1; then
+    install_packages zypper install \
+        mpv yt-dlp gcc cargo
 
-if command -v pacman >/dev/null; then
-    sudo pacman -S --needed --noconfirm mpv yt-dlp base-devel rust
-elif command -v apt >/dev/null; then
-    sudo apt install -y mpv yt-dlp build-essential cargo
-elif command -v dnf >/dev/null; then
-    sudo dnf install -y mpv yt-dlp gcc cargo
-elif command -v xbps-install >/dev/null; then
-    sudo xbps-install -Sy mpv yt-dlp base-devel cargo
 else
-    echo "unsupported package manager: install mpv, yt-dlp and cargo manually" >&2
+    echo "Error: unsupported package manager." >&2
+    echo "Install mpv, yt-dlp, a C compiler, and Cargo manually." >&2
     exit 1
 fi
 
+echo "-> Checking required commands..."
+
+for cmd in cargo mpv yt-dlp; do
+    if ! command -v "$cmd" >/dev/null 2>&1; then
+        echo "Error: $cmd was not found after installation." >&2
+        exit 1
+    fi
+done
+
+echo "-> Installing drift..."
+
 cargo install --git https://github.com/socatlolmeow/drift
+
+echo "-> Drift installation complete!"
+echo "Run 'drift' to start the application."
+echo "If the command is not found, pls check that ~/.cargo/bin is in your PATH"