feat(dist): ship via GitHub Release binaries + install.sh (drop npm as primary)

Distribute the prebuilt binary through GitHub Releases instead of the npm
registry — zero auth for the publisher (CI's GITHUB_TOKEN) and zero auth for
consumers (no npm token / 2FA / OTP, no GitHub Packages .npmrc).

- install.sh: detects OS/arch (incl. linux musl), downloads the matching
  agent-browser-<platform>.tar.gz from the GitHub Release, verifies .sha256,
  installs `agent-browser` + `abs` to /usr/local/bin or ~/.local/bin.
  Override via AGENT_BROWSER_VERSION / AGENT_BROWSER_BIN_DIR.
- .github/workflows/release-binaries.yml: on tag push (v*), build all 7
  platform variants (reusing the zigbuild cross-compile matrix), package each
  as .tar.gz + .sha256, attach to the tag's GitHub Release. No npm, no token.
- remove .github/workflows/release.yml: it published to npm (--provenance) and
  built the (removed) dashboard, so it broke on every main push.
- README install now leads with `curl … install.sh | sh`; npm demoted to a
  legacy alternative.
- skill stub self-heals: if `agent-browser` is missing, run install.sh (don't
  fall back to other browser tools).

install.sh

@@ -0,0 +1,100 @@
+#!/bin/sh
+# agent-browser-stealth installer — downloads the prebuilt binary from the
+# GitHub Release (no npm, no auth for you or your users).
+#
+#   curl -fsSL https://raw.githubusercontent.com/leeguooooo/agent-browser-stealth/main/install.sh | sh
+#
+# Env overrides:
+#   AGENT_BROWSER_VERSION=v0.27.0-fork.11   pin a specific release tag
+#   AGENT_BROWSER_BIN_DIR=/usr/local/bin    install location (auto-detected otherwise)
+set -eu
+
+REPO="leeguooooo/agent-browser-stealth"
+BIN_NAME="agent-browser"
+
+err() { printf '\033[31merror:\033[0m %s\n' "$1" >&2; exit 1; }
+info() { printf '\033[36m==>\033[0m %s\n' "$1" >&2; }
+
+command -v curl >/dev/null 2>&1 || err "curl is required"
+command -v tar >/dev/null 2>&1 || err "tar is required"
+
+# --- detect platform -> release asset name -------------------------------
+os=$(uname -s)
+arch=$(uname -m)
+case "$os" in
+  Darwin) plat="darwin" ;;
+  Linux)  plat="linux" ;;
+  *) err "unsupported OS: $os (use the Windows .exe asset from the Releases page)" ;;
+esac
+case "$arch" in
+  x86_64|amd64)   cpu="x64" ;;
+  arm64|aarch64)  cpu="arm64" ;;
+  *) err "unsupported architecture: $arch" ;;
+esac
+
+# musl (Alpine etc.) gets the statically-linked Linux build
+libc=""
+if [ "$plat" = "linux" ] && ! ldd /bin/sh 2>/dev/null | grep -qi 'gnu\|glibc'; then
+  if [ -e /lib/ld-musl-x86_64.so.1 ] || [ -e /lib/ld-musl-aarch64.so.1 ]; then
+    libc="-musl"
+  fi
+fi
+asset="agent-browser-${plat}${libc}-${cpu}"
+
+# --- resolve release tag --------------------------------------------------
+tag="${AGENT_BROWSER_VERSION:-}"
+if [ -z "$tag" ]; then
+  info "resolving latest release..."
+  tag=$(curl -fsSL "https://api.github.com/repos/${REPO}/releases/latest" \
+    | grep '"tag_name"' | head -1 | sed -E 's/.*"tag_name": *"([^"]+)".*/\1/')
+  [ -n "$tag" ] || err "could not resolve latest release tag (set AGENT_BROWSER_VERSION=vX.Y.Z)"
+fi
+
+base="https://github.com/${REPO}/releases/download/${tag}"
+tgz_url="${base}/${asset}.tar.gz"
+sha_url="${tgz_url}.sha256"
+
+# --- download + verify ----------------------------------------------------
+tmp=$(mktemp -d)
+trap 'rm -rf "$tmp"' EXIT
+info "downloading ${asset} (${tag})..."
+curl -fsSL "$tgz_url" -o "$tmp/pkg.tar.gz" \
+  || err "download failed: $tgz_url (is asset '${asset}.tar.gz' attached to release ${tag}?)"
+
+if curl -fsSL "$sha_url" -o "$tmp/pkg.sha256" 2>/dev/null; then
+  info "verifying checksum..."
+  expected=$(awk '{print $1}' "$tmp/pkg.sha256")
+  if command -v shasum >/dev/null 2>&1; then
+    actual=$(shasum -a 256 "$tmp/pkg.tar.gz" | awk '{print $1}')
+  elif command -v sha256sum >/dev/null 2>&1; then
+    actual=$(sha256sum "$tmp/pkg.tar.gz" | awk '{print $1}')
+  else
+    actual=""; info "no sha256 tool found, skipping verification"
+  fi
+  [ -z "$actual" ] || [ "$expected" = "$actual" ] || err "checksum mismatch (expected $expected, got $actual)"
+else
+  info "no .sha256 published, skipping verification"
+fi
+
+tar -xzf "$tmp/pkg.tar.gz" -C "$tmp"
+[ -f "$tmp/${BIN_NAME}" ] || err "archive did not contain ${BIN_NAME}"
+chmod +x "$tmp/${BIN_NAME}"
+
+# --- choose install dir ---------------------------------------------------
+bindir="${AGENT_BROWSER_BIN_DIR:-}"
+if [ -z "$bindir" ]; then
+  if [ -w /usr/local/bin ] 2>/dev/null; then bindir="/usr/local/bin"; else bindir="$HOME/.local/bin"; fi
+fi
+mkdir -p "$bindir"
+
+mv "$tmp/${BIN_NAME}" "$bindir/${BIN_NAME}"
+# convenience aliases: `abs` (short) -> agent-browser
+ln -sf "$bindir/${BIN_NAME}" "$bindir/abs" 2>/dev/null || true
+
+info "installed ${BIN_NAME} -> ${bindir}/${BIN_NAME}"
+"$bindir/${BIN_NAME}" --version 2>/dev/null || true
+
+case ":$PATH:" in
+  *":$bindir:"*) : ;;
+  *) printf '\033[33mnote:\033[0m %s is not on your PATH. Add:\n  export PATH="%s:$PATH"\n' "$bindir" "$bindir" >&2 ;;
+esac