Initial standalone dectalk 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 +1,20 @@
+#!/bin/bash
+# Start script for the DECTalk TTS server.
+# Installs node dependencies on first run, then runs the server.
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+cd "$SCRIPT_DIR"
+
+if ! command -v ffmpeg >/dev/null 2>&1; then
+    echo "Error: ffmpeg is not installed. Install it with: sudo apt install ffmpeg"
+    exit 1
+fi
+
+if [ ! -d node_modules ]; then
+    echo "Installing node dependencies..."
+    npm install
+fi
+
+export PORT="${PORT:-33001}"
+exec node server.js