Adds self-hosted update system

Implements a self-hosted update mechanism, allowing the application to be updated from a corporate network share without relying on third-party services.

This includes:
- Functionality to check for updates
- Download installers
- Verify checksums
- Install updates with UAC elevation

Configuration is managed via the config.ini file, with automatic checks on startup. A new settings UI is also included.

installer/sample_version.json

@@ -0,0 +1,14 @@
+{
+  "stableVersion": "1.4.0",
+  "betaVersion": "1.4.1-beta",
+  "stableDownload": "EMLy_Installer_1.4.0.exe",
+  "betaDownload": "EMLy_Installer_1.4.1-beta.exe",
+  "sha256Checksums": {
+    "EMLy_Installer_1.4.0.exe": "put_sha256_hash_here",
+    "EMLy_Installer_1.4.1-beta.exe": "put_sha256_hash_here"
+  },
+  "releaseNotes": {
+    "1.4.0": "Initial release with self-hosted update system",
+    "1.4.1-beta": "Beta release with bug fixes"
+  }
+}