Add headless streaming mode + Mac client + full docs

Headless mode (new) — for KVM-attached hosts streaming to disconnected clients
- --headless / --mirror flags; default headless on hostname JARVIS, mirror elsewhere
- New lib/headless.sh installs prep-cmd hooks to ~/.local/share/omarchy-moonlight/bin
- bin/sunshine-stream-do.sh creates/resizes a Hyprland HEADLESS-1 output to the
  connecting client's resolution and migrates the active workspace onto it
- bin/sunshine-stream-undo.sh tears down the headless output on disconnect and
  returns the workspace to a non-headless monitor when one is available
- lib/config.sh writes capture=wlr, output_name=HEADLESS-1, and the JSON
  global_prep_cmd entry referencing the installed hook paths
- lib/preflight.sh adds a preflight_headless step that checks hyprctl, jq, and
  a running Hyprland session (warn-only, install can proceed)
- lib/verify.sh adds checks for the hook scripts and the wlr/global_prep_cmd
  config lines

Mac client
- client/install-macos.sh: Darwin guard, Homebrew presence check, brew cask
  install of Moonlight, idempotent
- client/README.md: per-platform install (macOS / Android / iOS / Apple TV /
  Linux + Steam Deck) and the five-step first-pair walkthrough

Other
- jq added to the helper install set in lib/packages.sh (hooks parse Hyprland
  JSON output)
- README.md rewritten to cover both modes, the new flags, the tuned defaults
  per mode + per vendor, the headless internals, and the client pointer

client/install-macos.sh

@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+# Install Moonlight on macOS via Homebrew cask.
+# Standalone: does not source lib/common.sh (intended to run on a Mac that
+# may not have the full repo checked out yet).
+
+set -euo pipefail
+
+if [[ -t 1 ]]; then
+  BOLD=$'\033[1m'
+  RED=$'\033[31m'
+  GREEN=$'\033[32m'
+  YELLOW=$'\033[33m'
+  BLUE=$'\033[34m'
+  RESET=$'\033[0m'
+else
+  BOLD="" RED="" GREEN="" YELLOW="" BLUE="" RESET=""
+fi
+
+step() { printf '\n%s==>%s %s%s%s\n' "$BLUE" "$RESET" "$BOLD" "$*" "$RESET"; }
+info() { printf '  %s\n' "$*"; }
+ok()   { printf '  %s✓%s %s\n' "$GREEN" "$RESET" "$*"; }
+warn() { printf '  %s!%s %s\n' "$YELLOW" "$RESET" "$*" >&2; }
+err()  { printf '  %s✗%s %s\n' "$RED" "$RESET" "$*" >&2; }
+
+# Refuse to run anywhere but macOS.
+if [[ "$(uname -s)" != "Darwin" ]]; then
+  err "This script only runs on macOS (Darwin). Detected: $(uname -s)"
+  exit 1
+fi
+
+step "Checking for Homebrew"
+if ! command -v brew >/dev/null 2>&1; then
+  err "Homebrew is not installed."
+  info "Install it with the official one-liner, then re-run this script:"
+  info ""
+  info '  /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"'
+  info ""
+  info "See https://brew.sh for details."
+  exit 1
+fi
+ok "Homebrew found: $(command -v brew)"
+
+step "Installing Moonlight (brew cask)"
+# brew install --cask is idempotent: re-running on an already-installed cask
+# is a no-op and exits 0.
+if brew install --cask moonlight; then
+  ok "Moonlight installed (or already present)."
+else
+  err "brew install --cask moonlight failed."
+  warn "Try: brew update && brew install --cask moonlight"
+  exit 1
+fi
+
+step "Next steps"
+info "App location:  /Applications/Moonlight.app"
+info "Launch:        open -a Moonlight"
+info ""
+info "Pair this Mac with your Sunshine host by following the walkthrough in:"
+info "  client/README.md"
+info ""
+ok "Done."