Add one-click launcher and interactive setup wizard

- setup.py: prompts only for the values the user must choose, generates a
  random auth_key, writes config.json (backs up any existing one).
- start.bat / start.sh: create a local venv, install deps (with PyPI mirror
  fallback), run the wizard if config.json is missing, then launch main.py.
- main.py: when config.json is missing on an interactive TTY, offer to run
  the wizard instead of just exiting.
- README: new "Quick Start" section up top; manual steps kept below.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

start.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+# MasterHttpRelayVPN one-click launcher (Linux / macOS)
+# Creates a local virtualenv, installs deps, runs the setup wizard
+# if needed, then starts the proxy.
+
+set -e
+cd "$(dirname "$0")"
+
+VENV_DIR=".venv"
+
+find_python() {
+    for cmd in python3.12 python3.11 python3.10 python3 python; do
+        if command -v "$cmd" >/dev/null 2>&1; then
+            ver=$("$cmd" -c 'import sys;print("%d.%d"%sys.version_info[:2])' 2>/dev/null || echo "0.0")
+            major=${ver%.*}; minor=${ver#*.}
+            if [ "$major" -ge 3 ] && [ "$minor" -ge 10 ]; then
+                echo "$cmd"
+                return 0
+            fi
+        fi
+    done
+    return 1
+}
+
+PY=$(find_python) || {
+    echo "[X] Python 3.10+ not found. Install it and re-run this script." >&2
+    exit 1
+}
+
+if [ ! -x "$VENV_DIR/bin/python" ]; then
+    echo "[*] Creating virtual environment in $VENV_DIR ..."
+    "$PY" -m venv "$VENV_DIR"
+fi
+
+VPY="$VENV_DIR/bin/python"
+
+echo "[*] Installing dependencies ..."
+"$VPY" -m pip install --disable-pip-version-check -q --upgrade pip >/dev/null
+if ! "$VPY" -m pip install --disable-pip-version-check -q -r requirements.txt; then
+    echo "[!] PyPI install failed. Retrying via runflare mirror ..."
+    "$VPY" -m pip install --disable-pip-version-check -q -r requirements.txt \
+        -i https://mirror-pypi.runflare.com/simple/ \
+        --trusted-host mirror-pypi.runflare.com
+fi
+
+if [ ! -f "config.json" ]; then
+    echo "[*] No config.json found — launching setup wizard ..."
+    "$VPY" setup.py
+fi
+
+echo
+echo "[*] Starting MasterHttpRelayVPN ..."
+echo
+exec "$VPY" main.py "$@"