build(proxy_app): 📦 include setuptools/distutils in build and clarify launcher missing .env message

- Remove "--exclude-module=setuptools" and "--exclude-module=distutils" from PyInstaller args to allow those modules to be packaged.
- Update launcher TUI prompt to stop referencing `PROXY_API_KEY` and only require a `.env` file, simplifying and clarifying the startup message.

src/proxy_app/build.py

@@ -52,8 +52,6 @@ def main():
         "--exclude-module=jupyter",
         "--exclude-module=notebook",
         "--exclude-module=PIL.ImageTk",
-        "--exclude-module=setuptools",
-        "--exclude-module=distutils",
         # Optimization: Enable UPX compression (if available)
         "--upx-dir=upx" if platform.system() != "Darwin" else "--noupx",  # macOS has issues with UPX
         # Optimization: Strip debug symbols (smaller binary)

src/proxy_app/launcher_tui.py

@@ -574,7 +574,7 @@ class LauncherTUI:
             self.console.print(Panel(
                 Text.from_markup(
                     "⚠️  [bold yellow]Setup Required[/bold yellow]\n\n"
-                    "Cannot start without .env and PROXY_API_KEY.\n"
+                    "Cannot start without .env.\n"
                     "Launching credential tool..."
                 ),
                 border_style="yellow"