Initial standalone vox TTS server extracted from the ttstoy bot cog

Self-contained HTTP service with engine, data, start script, systemd unit,
and documentation. Runs independently of the Discord bot on its fixed port.

start.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+# Start script for the VOX TTS server.
+# The server uses only the Python standard library, so no venv is required.
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+cd "$SCRIPT_DIR"
+
+export PORT="${PORT:-33003}"
+exec python3 "$SCRIPT_DIR/server.py"