Enhance branding and release workflows

- Updated README.md to include a reference to branding and releases documentation.
- Modified brand_config.py to support multi-brand packaging, including functions for collecting local release data and merging release manifests.
- Adjusted build_macos.sh to set a default brand if none is specified and updated DMG naming conventions.
- Enhanced create_release.ps1 and create_release.sh scripts to support dry-run functionality and improved artifact handling.
- Added a new template for brand configuration in build/brands/template.jsonc.
- Created comprehensive branding and releases documentation in docs/BRANDING_AND_RELEASES.md.
- Added unit tests for new branding functionalities in test_brand_config.py.

build/brands/template.jsonc

@@ -0,0 +1,20 @@
+{
+  // Copy this file to build/brands/<your-brand>.json (without comments)
+  // and replace values.
+  "brand_id": "your_brand_id",
+  "display_name": "Your Brand Bridge",
+  "asset_prefix": "YourBrandBridge",
+  "exe_name": "YourBrandBridge",
+  "manufacturer": "Your Company",
+  "install_dir_name": "Your Brand Bridge",
+  "shortcut_description": "Your brand drag-and-drop bridge",
+  "bundle_identifier": "com.yourcompany.bridge",
+  "config_dir_name": "your_brand_bridge",
+  "msi_upgrade_code": "00000000-0000-0000-0000-000000000000",
+  "update_channel": "stable",
+  "icon_ico": "resources/icons/app.ico",
+  "icon_icns": "resources/icons/app.icns",
+  "dialog_bmp": "resources/icons/background.bmp",
+  "banner_bmp": "resources/icons/banner.bmp",
+  "license_rtf": "resources/license.rtf"
+}