Move installer scripts into scripts/ directory

- install.sh, uninstall.sh, dev-setup.sh now live under scripts/.
- dev-setup.sh's 'cd $(dirname $0)' updated to '.../..' so it lands
  at the repo root regardless of CWD.
- README install/uninstall curl URLs now reference scripts/<name>.sh.
- README contributor section and Files table updated to match.

Behavior is unchanged. The curl one-liner URL changes from
.../master/install.sh to .../master/scripts/install.sh; users following
the pre-v1.0.2 README will get a 404 from the old URL.

scripts/dev-setup.sh

@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+#
+# dev-setup.sh - contributor bootstrap for the `move` repo.
+#
+# Use this when you have cloned the repo and want a working development
+# environment. End users should use `install.sh` (curl-pipeable) instead.
+#
+# Verifies Bun is installed, then runs `bun install` to fetch dependencies
+# (notably `@nut-tree-fork/nut-js`, which ships prebuilt native binaries
+# for darwin-arm64/x64, linux, and windows).
+#
+# This script is idempotent: re-running it just re-resolves the dependency
+# tree against the existing `bun.lock`.
+
+# Fail fast on any error, unset variable, or failed pipe stage.
+set -euo pipefail
+
+# Operate at the repo root regardless of the caller's CWD. This script lives
+# under scripts/, so pop up one level to land at the project root before
+# running bun install.
+cd "$(dirname "$0")/.."
+
+echo "==> Checking for Bun..."
+if ! command -v bun >/dev/null 2>&1; then
+    # Hard error rather than auto-install: keep the script's behavior
+    # predictable and let the user pick their own install method.
+    echo "Error: bun is not installed." >&2
+    echo "       Install it from https://bun.sh (e.g. 'brew install oven-sh/bun/bun') and re-run." >&2
+    exit 1
+fi
+echo "    bun $(bun --version)"
+
+echo "==> Installing dependencies..."
+bun install
+
+echo
+echo "Done. Dev workflow:"
+echo "  - 'bun run start' to run from the source tree."
+echo "  - 'bun link' to install a global 'move' command pointed at this checkout."
+echo "End-user installer is install.sh (curl-pipeable from Gitea)."
+
+# macOS gates synthetic mouse events behind the Accessibility permission.
+# Without this hint, the first run silently fails to move the cursor and
+# the user has no obvious next step.
+if [[ "$(uname)" == "Darwin" ]]; then
+    echo "Note: macOS will prompt for Accessibility permission on first mouse move."
+    echo "      Grant it under System Settings > Privacy & Security > Accessibility."
+fi