Add brand-specific update channel and environment configuration

- Updated `brand_config.py` to include `WEBDROP_UPDATE_CHANNEL` in the environment variables.
- Enhanced `build_macos.sh` to create a bundled `.env` file with brand-specific defaults, including the update channel.
- Implemented a method in `build_windows.py` to create a bundled `.env` file for Windows builds, incorporating brand-specific runtime defaults.
- Modified `config.py` to ensure the application can locate the `.env` file in various installation scenarios.
- Added unit tests in `test_config.py` to verify the loading of the bootstrap `.env` from the PyInstaller runtime directory.
- Generated new WiX object and script files for the Windows installer, including application shortcuts and registry entries.

build/scripts/build_windows.py

@@ -38,6 +38,8 @@ import argparse
 from pathlib import Path
 from datetime import datetime
 
+from dotenv import dotenv_values
+
 # Import shared version utilities
 from brand_config import load_brand_config
 from sync_version import get_current_version, do_sync_version
@@ -95,6 +97,44 @@ class WindowsBuilder:
                 shutil.rmtree(path)
                 print(f"  Removed {path}")
 
+    @staticmethod
+    def _format_env_value(value: str) -> str:
+        """Format env values safely for .env files."""
+        if any(ch in value for ch in [" ", "#", '"', "'", "\t"]):
+            escaped = value.replace("\\", "\\\\").replace('"', '\\"')
+            return f'"{escaped}"'
+        return value
+
+    def _create_bundled_env_file(self) -> Path:
+        """Create a bundled .env file with brand-specific runtime defaults."""
+        values = dotenv_values(self.env_file)
+        overrides = {
+            "APP_NAME": self.brand.display_name,
+            "BRAND_ID": self.brand.brand_id,
+            "APP_CONFIG_DIR_NAME": self.brand.config_dir_name,
+            "UPDATE_CHANNEL": self.brand.update_channel,
+        }
+
+        output_env = self.temp_dir / ".env"
+        output_env.parent.mkdir(parents=True, exist_ok=True)
+
+        lines: list[str] = []
+        for key, raw_value in values.items():
+            if key in overrides:
+                continue
+            if raw_value is None:
+                lines.append(key)
+            else:
+                lines.append(f"{key}={self._format_env_value(str(raw_value))}")
+
+        lines.append("")
+        lines.append("# Brand-specific defaults added during packaging")
+        for key, value in overrides.items():
+            lines.append(f"{key}={self._format_env_value(value)}")
+
+        output_env.write_text("\n".join(lines) + "\n", encoding="utf-8")
+        return output_env
+
     def build_executable(self) -> bool:
         """Build executable using PyInstaller."""
         print("\n🔨 Building Windows executable with PyInstaller...")
@@ -119,7 +159,7 @@ class WindowsBuilder:
 
         # Set environment variable for spec file to use
         env = os.environ.copy()
-        env["WEBDROP_ENV_FILE"] = str(self.env_file)
+        env["WEBDROP_ENV_FILE"] = str(self._create_bundled_env_file())
         env["WEBDROP_BRAND_ID"] = self.brand.brand_id
         env["WEBDROP_APP_DISPLAY_NAME"] = self.brand.display_name
         env["WEBDROP_ASSET_PREFIX"] = self.brand.asset_prefix