added install script

install.sh

@@ -0,0 +1,43 @@
+#!/bin/sh
+set -eu
+
+HOST="https://git.briannelson.dev"   # your Gitea URL, no trailing slash
+REPO="brian/rusty-pw"
+BIN="rusty-pw"
+DIR="$HOME/.local/bin"
+
+# Only Apple Silicon Macs are supported for now. Fail clearly otherwise.
+if [ "$(uname -s)" != "Darwin" ] || [ "$(uname -m)" != "arm64" ]; then
+  echo "This installer only supports macOS on Apple Silicon." >&2
+  exit 1
+fi
+
+# Ask Gitea for the newest release tag.
+tag=$(curl -fsSL "$HOST/api/v1/repos/$REPO/releases/latest" \
+  | sed -n 's/.*"tag_name": *"\([^"]*\)".*/\1/p' | head -n 1)
+
+if [ -z "$tag" ]; then
+  echo "Could not find a release for $REPO" >&2
+  exit 1
+fi
+
+# Download and install. curl downloads aren't quarantined, so no Gatekeeper prompt.
+mkdir -p "$DIR"
+echo "Downloading $BIN $tag..."
+curl -fsSL "$HOST/$REPO/releases/download/$tag/$BIN-macos-arm64" -o "$DIR/$BIN"
+chmod +x "$DIR/$BIN"
+
+# Put the install folder on PATH for future terminals (zsh is the macOS default).
+case ":$PATH:" in
+  *":$DIR:"*) ;;
+  *)
+    rc="$HOME/.zshrc"
+    line='export PATH="$HOME/.local/bin:$PATH"'
+    if ! grep -qsF "$line" "$rc"; then
+      echo "$line" >> "$rc"
+    fi
+    echo "Added $DIR to PATH in $rc. Open a new terminal window to use it."
+    ;;
+esac
+
+echo "Installed $BIN $tag. Run: $BIN"