refactor(app): rename GitLite to Gitty throughout the application

The application has been rebranded from GitLite to Gitty, which involved
updating various references across the codebase, including titles,
descriptions, and identifiers. This change reflects the new branding
strategy and ensures consistency in the user interface and backend.

- Updated project name and identifiers in configuration files
- Changed all instances of "GitLite" to "Gitty" in HTML and Svelte files
- Adjusted descriptions and help texts to match the new branding

src-tauri/tauri.conf.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
-  "productName": "GitLite",
+  "productName": "Gitty",
   "version": "2026.7.16",
   "identifier": "com.git-lite",
   "build": {
@@ -13,7 +13,7 @@
     "windows": [
       {
         "label": "main",
-        "title": "GitLite",
+        "title": "Gitty",
         "width": 1200,
         "height": 800,
         "minWidth": 900,
@@ -25,7 +25,7 @@
       {
         "label": "splashscreen",
         "url": "splashscreen.html",
-        "title": "GitLite",
+        "title": "Gitty",
         "width": 460,
         "height": 420,
         "resizable": false,