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.

internal/lib/Logging.ps1

@@ -0,0 +1,38 @@
+# Logging.ps1 — shared logging utility
+# Requires $InternalRoot to be defined in the calling script's scope before dot-sourcing.
+
+function Write-Log {
+    [CmdletBinding()]
+    param(
+        [ValidateSet('Info', 'Warn', 'Error')]
+        [string]$Level = 'Info',
+
+        [Parameter(Mandatory)]
+        [string]$Message,
+
+        [string]$Feature = 'General'
+    )
+
+    $logDir = Join-Path $InternalRoot 'data\logs'
+    if (-not (Test-Path $logDir)) {
+        New-Item -ItemType Directory -Path $logDir -Force | Out-Null
+    }
+
+    $logFile  = Join-Path $logDir "automation-$(Get-Date -Format 'yyyy-MM-dd').log"
+    $timestamp = Get-Date -Format 'yyyy-MM-dd HH:mm:ss'
+    $levelPad  = $Level.ToUpper().PadRight(5)
+    $line      = "[$timestamp] [$levelPad] [$Feature] $Message"
+
+    try {
+        Add-Content -Path $logFile -Value $line -Encoding UTF8 -ErrorAction Stop
+    }
+    catch {
+        # Logging must never crash the caller — silently ignore write failures
+    }
+
+    # Rotate: remove logs older than 7 days
+    Get-ChildItem -Path $logDir -Filter 'automation-*.log' -ErrorAction SilentlyContinue |
+        Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-7) } |
+        Remove-Item -Force -ErrorAction SilentlyContinue
+}
+