Add curl-pipe installer, uninstaller, and contributor bootstrap

End-user installation collapses to a single command:

  curl -fsSL https://gitea.cahlen.com/nokeo08/Move/raw/branch/master/install.sh | sh

Changes:

- install.sh rewritten as a POSIX sh, curl-pipeable end-user installer.
  Honors XDG_DATA_HOME and XDG_BIN_HOME (de facto). Idempotent via a
  version-marker file at $INSTALL_DIR/.installed-version; MOVE_FORCE=1
  overrides. Hard-fails if Bun is missing (no auto-install). Includes
  a safety guard refusing rm -rf on too-broad install dirs.
- uninstall.sh added; same curl-pipe pattern, shared XDG path
  resolution, leaves Bun alone.
- dev-setup.sh added (= the previous install.sh content, retitled for
  contributors and pointing at bun run start / bun link / install.sh).
- README updated: curl one-liner Install section, XDG behavior tables,
  new Uninstall section, new 'For contributors' section, Files table
  rows for all three scripts.

dev-setup.sh

@@ -0,0 +1,47 @@
+#!/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
+
+# Always operate relative to the script's own directory so the install works
+# regardless of the caller's CWD.
+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