feat(integrations): add Git hosting providers and Clone UI

Add integrations for GitHub, GitLab (cloud & self-hosted), Azure DevOps,
and Gitea, storing personal access tokens in the operating system
keychain. Azure DevOps supports multiple independently configurable
organizations, and the Clone → Integrations tab loads, filters, sorts,
and clones repositories using stored credentials. Update the API
contract, help overlay, README, changelog, and application version
metadata to document and ship the feature.

- Add list_integration_repositories API command and related types
- New Clone → Integrations UI with search, refresh, and direct clone
- Store tokens in OS keychain and support multiple Azure DevOps orgs

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "Gitty",
-  "version": "2026.8.7",
+  "version": "2026.8.8",
   "identifier": "com.gitty",
   "build": {
     "beforeDevCommand": "npm run prepare:lfs && npm run dev",