run.sh: launch the built client against a local install

`WOW_DATA` names the install, defaulting to the TurtleWoW one, and `WOW_HOST` overrides the
realm for a single run without touching `benilla-config/config.toml`. Builds the release
binary first if it is not there, then execs it, so the run line is one command.

run.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# Launch the built benilla client against the local TurtleWoW install.
+#
+#   ./run.sh                 # release build, TurtleWoW data, saved settings
+#   ./run.sh --release       # (same; argument is passed through to the client)
+#   WOW_DATA=/path/to/Data ./run.sh
+#   WOW_HOST=logon.turtle-wow.org ./run.sh
+#
+# The realm comes from benilla-config/config.toml (or the Realmlist button on the login
+# screen). Set WOW_HOST to override it for this run without touching the file; set WOW_USER
+# and WOW_PASS to skip the login screen.
+set -euo pipefail
+
+root="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$root"
+
+# The game data folder. Defaults to the TurtleWoW install; override with WOW_DATA.
+: "${WOW_DATA:=$HOME/Documents/TurtleWoW/Data}"
+export WOW_DATA
+if [ ! -d "$WOW_DATA" ]; then
+    echo "run: no Data folder at $WOW_DATA — set WOW_DATA=/path/to/WoW/Data" >&2
+    exit 1
+fi
+
+bin="$root/target/release/benilla"
+if [ ! -x "$bin" ]; then
+    echo "run: $bin is missing; building (release)…"
+    cargo build --release -p benilla
+fi
+
+echo "run: $bin  (data: $WOW_DATA${WOW_HOST:+, realm: $WOW_HOST})"
+exec "$bin" "$@"