Add installation script

- Created install.sh to automate the download and installation of trigrep.
- Added logic to detect OS and architecture for proper binary selection.
- Implemented automated version resolution and checksum verification.
- Configured default installation path detection for macOS and Linux.

Author: PythonicNinja

scripts/install.sh

@@ -0,0 +1,166 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+TRIGREP_REPO="${TRIGREP_REPO:-PythonicNinja/trigrep}"
+TRIGREP_VERSION="${TRIGREP_VERSION:-}"
+TRIGREP_INSTALL_DIR="${TRIGREP_INSTALL_DIR:-}"
+
+require_tool() {
+  if ! command -v "$1" >/dev/null 2>&1; then
+    echo "error: required tool not found: $1" >&2
+    exit 1
+  fi
+}
+
+sha256_file() {
+  local file="$1"
+
+  if command -v sha256sum >/dev/null 2>&1; then
+    sha256sum "$file" | awk '{print $1}'
+    return
+  fi
+
+  if command -v shasum >/dev/null 2>&1; then
+    shasum -a 256 "$file" | awk '{print $1}'
+    return
+  fi
+
+  echo "error: no SHA256 tool found (need sha256sum or shasum)" >&2
+  exit 1
+}
+
+resolve_latest_version() {
+  local latest_url="https://github.com/${TRIGREP_REPO}/releases/latest"
+  local final_url
+
+  final_url="$(curl -fsSLI -o /dev/null -w '%{url_effective}' "$latest_url")"
+  basename "$final_url"
+}
+
+detect_target() {
+  local os
+  local arch
+
+  os="$(uname -s)"
+  arch="$(uname -m)"
+
+  case "$os" in
+    Linux)
+      case "$arch" in
+        x86_64)
+          echo "x86_64-unknown-linux-gnu"
+          ;;
+        aarch64|arm64)
+          echo "aarch64-unknown-linux-gnu"
+          ;;
+        *)
+          echo "error: unsupported Linux architecture: $arch" >&2
+          exit 1
+          ;;
+      esac
+      ;;
+    Darwin)
+      case "$arch" in
+        x86_64)
+          echo "x86_64-apple-darwin"
+          ;;
+        arm64|aarch64)
+          echo "aarch64-apple-darwin"
+          ;;
+        *)
+          echo "error: unsupported macOS architecture: $arch" >&2
+          exit 1
+          ;;
+      esac
+      ;;
+    *)
+      echo "error: unsupported OS: $os (this installer supports macOS and Linux)" >&2
+      exit 1
+      ;;
+  esac
+}
+
+select_install_dir() {
+  if [ -n "$TRIGREP_INSTALL_DIR" ]; then
+    echo "$TRIGREP_INSTALL_DIR"
+    return
+  fi
+
+  if [ -d "/usr/local/bin" ] && [ -w "/usr/local/bin" ]; then
+    echo "/usr/local/bin"
+    return
+  fi
+
+  echo "${HOME}/.local/bin"
+}
+
+require_tool curl
+require_tool tar
+
+TARGET="$(detect_target)"
+VERSION="${TRIGREP_VERSION}"
+if [ -z "$VERSION" ]; then
+  VERSION="$(resolve_latest_version)"
+fi
+
+INSTALL_DIR="$(select_install_dir)"
+mkdir -p "$INSTALL_DIR"
+if [ ! -w "$INSTALL_DIR" ]; then
+  echo "error: install directory is not writable: $INSTALL_DIR" >&2
+  echo "set TRIGREP_INSTALL_DIR to a writable directory" >&2
+  exit 1
+fi
+
+ASSET="trigrep-${VERSION}-${TARGET}.tar.gz"
+BASE_URL="https://github.com/${TRIGREP_REPO}/releases/download/${VERSION}"
+ASSET_URL="${BASE_URL}/${ASSET}"
+CHECKSUMS_URL="${BASE_URL}/checksums.txt"
+
+TMP_DIR="$(mktemp -d "${TMPDIR:-/tmp}/trigrep-install.XXXXXX")"
+trap 'rm -rf "$TMP_DIR"' EXIT
+
+ARCHIVE_PATH="${TMP_DIR}/${ASSET}"
+CHECKSUMS_PATH="${TMP_DIR}/checksums.txt"
+
+echo "==> Installing trigrep ${VERSION} (${TARGET})"
+echo "==> Downloading ${ASSET_URL}"
+curl -fsSL --retry 3 -o "$ARCHIVE_PATH" "$ASSET_URL"
+
+echo "==> Downloading ${CHECKSUMS_URL}"
+if curl -fsSL --retry 3 -o "$CHECKSUMS_PATH" "$CHECKSUMS_URL"; then
+  EXPECTED_SHA="$(awk -v name="$ASSET" '$2 == name { print $1 }' "$CHECKSUMS_PATH")"
+  if [ -z "$EXPECTED_SHA" ]; then
+    echo "error: checksum for ${ASSET} not found in checksums.txt" >&2
+    exit 1
+  fi
+
+  ACTUAL_SHA="$(sha256_file "$ARCHIVE_PATH")"
+  if [ "$EXPECTED_SHA" != "$ACTUAL_SHA" ]; then
+    echo "error: checksum mismatch for ${ASSET}" >&2
+    echo "expected: $EXPECTED_SHA" >&2
+    echo "actual:   $ACTUAL_SHA" >&2
+    exit 1
+  fi
+
+  echo "==> Checksum verified"
+else
+  echo "==> Warning: checksums.txt not found for ${VERSION}; skipping checksum verification" >&2
+fi
+tar -xzf "$ARCHIVE_PATH" -C "$TMP_DIR"
+
+if [ ! -f "${TMP_DIR}/trigrep" ]; then
+  echo "error: trigrep binary not found in archive" >&2
+  exit 1
+fi
+
+install -m 0755 "${TMP_DIR}/trigrep" "${INSTALL_DIR}/trigrep"
+
+echo "==> Installed to ${INSTALL_DIR}/trigrep"
+"${INSTALL_DIR}/trigrep" --version
+
+case ":$PATH:" in
+  *":${INSTALL_DIR}:"*) ;;
+  *)
+    echo "==> Add ${INSTALL_DIR} to your PATH if needed"
+    ;;
+esac