Optimize installer: preflight checks, tuned conf, doctor, faster default

Layers a few things on top of the initial scaffold:

- Default to sunshine-bin (precompiled, ~seconds) instead of building from
  source. --from-source restores the old behavior.
- Add lib/preflight.sh: catches the gotchas before any work is done —
  Wayland session, NVIDIA driver responsive, nvidia-drm.modeset, amdgpu
  loaded, pipewire-pulse present, SSH-without-session warning.
- Add lib/config.sh: writes a tuned ~/.config/sunshine/sunshine.conf with
  per-vendor encoder settings (NVENC P1+ll+cbr, VAAPI ultralowlatency,
  QuickSync veryfast), KMS capture, pulse audio sink. Uses a
  "# managed-by: omarchy-moonlight" marker; removing it hands ownership
  back to the user and the installer won't touch the file again.
- Add lib/verify.sh: post-install verification of every step
  (cap_sys_admin set, group resolves, udev rule present, /dev/uinput
  exists, encoder reachable, service active, :47990 listening). Same
  checks are reachable standalone via --doctor.
- Install runtime helpers (pipewire-pulse, vulkan-tools, libva-utils)
  alongside Sunshine for diagnostics + audio.
- Uninstall handles both sunshine + sunshine-bin and the -bin moonlight
  variant.
- README documents the tuning table, the new flags, and the modeset
  troubleshooting path.

lib/preflight.sh

@@ -0,0 +1,98 @@
+#!/usr/bin/env bash
+# Preflight: catch problems before we install anything.
+# Fail fast and loud, with remediation hints.
+
+preflight_all() {
+  preflight_session
+  preflight_remote_session
+  preflight_gpu
+  preflight_kms_modeset
+  preflight_audio
+}
+
+preflight_session() {
+  if [[ "${SESSION_TYPE:-}" != "wayland" ]]; then
+    warn "Session type '$SESSION_TYPE' — KMS capture works at the DRM level so it can still succeed,"
+    warn "but this installer's defaults assume Hyprland on Wayland."
+  else
+    ok "Wayland session detected"
+  fi
+}
+
+preflight_remote_session() {
+  # Sunshine's user service needs the local Wayland session to be reachable.
+  # If we're over pure SSH (no forwarded DBUS / WAYLAND_DISPLAY), the service start
+  # at the end of the install will fail. Warn now so the user knows.
+  if [[ -n "${SSH_CONNECTION:-}" && -z "${WAYLAND_DISPLAY:-}" && -z "${DISPLAY:-}" ]]; then
+    warn "Running over SSH without a graphical session. Packages will install,"
+    warn "but the systemd --user service will only come up cleanly once you log in"
+    warn "to Hyprland on the console. That's fine — just log in afterwards."
+  fi
+}
+
+preflight_gpu() {
+  case "$GPU_VENDOR" in
+    nvidia)
+      if ! command -v nvidia-smi >/dev/null 2>&1; then
+        warn "nvidia-smi not found yet — nvidia-utils will be installed shortly."
+        return 0
+      fi
+      if ! nvidia-smi -L >/dev/null 2>&1; then
+        err "nvidia-smi exists but can't talk to the driver. Driver not loaded?"
+        err "Check: 'lsmod | grep nvidia' and 'dmesg | grep -i nvidia'"
+        exit 1
+      fi
+      ok "NVIDIA driver responsive ($(nvidia-smi -L | head -n1))"
+      ;;
+    amd)
+      if ! lsmod | grep -q '^amdgpu'; then
+        warn "amdgpu kernel module not loaded. Hardware encode (VAAPI) will likely fail until it is."
+      else
+        ok "amdgpu kernel module loaded"
+      fi
+      ;;
+    intel)
+      ok "Intel GPU — will install intel-media-driver"
+      ;;
+  esac
+}
+
+preflight_kms_modeset() {
+  # KMS capture needs nvidia-drm.modeset=1 on NVIDIA. Driver 560+ defaults to 1,
+  # but if the user is on something older or has explicitly set 0, capture will fail.
+  [[ "$GPU_VENDOR" == "nvidia" ]] || return 0
+
+  # Cmdline check is read-only and reliable when explicitly set.
+  if grep -q 'nvidia-drm.modeset=1' /proc/cmdline; then
+    ok "nvidia-drm.modeset=1 set on kernel cmdline"
+    return 0
+  fi
+  if grep -q 'nvidia-drm.modeset=0' /proc/cmdline; then
+    err "nvidia-drm.modeset=0 is set on the kernel cmdline. KMS capture WILL fail."
+    err "Remove it (e.g., from /boot/loader/entries/*.conf or /etc/kernel/cmdline + reinstall-kernels)"
+    err "and reboot before running this installer."
+    exit 1
+  fi
+
+  # Not on cmdline — check the runtime parameter. On 560+ this defaults to Y.
+  # /sys file is root-readable; modinfo gives the default without sudo.
+  local default=""
+  if command -v modinfo >/dev/null 2>&1; then
+    default="$(modinfo -F parm nvidia_drm 2>/dev/null | awk -F: '/^modeset:/ {print $2}' | head -n1 || true)"
+  fi
+  if [[ -n "$default" ]]; then
+    info "nvidia_drm modeset default per modinfo: ${default## }"
+  fi
+  warn "nvidia-drm.modeset=1 not explicitly set on cmdline."
+  warn "Modern drivers (≥560) default to enabled, so this is usually fine — but if KMS"
+  warn "capture fails after install, add 'nvidia-drm.modeset=1' to your kernel cmdline."
+}
+
+preflight_audio() {
+  # Sunshine captures audio via the PulseAudio API; on Omarchy that's pipewire-pulse.
+  if pkg_installed pipewire-pulse; then
+    ok "pipewire-pulse present (audio capture path OK)"
+  else
+    warn "pipewire-pulse is not installed. Audio capture may not work until it is."
+  fi
+}