Add new features: DefaultBrowser, DynamicLock, SandwichReminder

- Implemented DefaultBrowser feature to notify users when the default browser does not match the configured app.
- Added DynamicLock feature to disable Dynamic Lock while connected to a specific network and re-enable it after disconnecting.
- Created SandwichReminder feature to prompt users to order a sandwich during work hours based on network and time settings.

Introduced helper libraries for configuration, elevation, logging, network utilities, and toast notifications.

- Config.ps1: Added functions for reading and writing configuration and state files.
- Elevation.ps1: Added functions to check for administrator privileges and request elevation.
- Logging.ps1: Implemented a shared logging utility for consistent logging across features.
- NetworkUtils.ps1: Added a function to check for DNS suffix connectivity.
- ToastHelper.ps1: Created a helper for displaying Windows toast notifications.

Implemented runner.ps1 as the main entry point for executing features based on configuration.

.gitignore

@@ -0,0 +1,16 @@
+# Logs directory (daily rotating logs + diagnostics)
+internal/data/logs/
+
+# Runtime state per-feature
+internal/data/state/
+
+# Result JSON files (auto-created)
+internal/data/*.json
+
+# IDEs
+.vscode/
+.idea/
+
+# OS
+.DS_Store
+Thumbs.db