feat(startup): enable startup clone requests from CLI and IPC

Adds startup clone support with a new clone request type and parsing.
It wires a CLI and IPC pathway to forward a clone to a running app.
UI and docs were updated to reflect startup clone behavior.

- Introduce StartupCloneRequest and argument parsing.
- Wire IPC to pass clone requests and clone on startup.
- UI updated to queue clone requests and trigger clone.

README.md

@@ -82,6 +82,27 @@ files.
 
 ---
 
+## Command line
+
+Open an existing repository when Gitty starts:
+
+```text
+gitty.exe --repo "D:\Projects\ExistingRepo"
+```
+
+Clone a remote into an exact local target folder and open it immediately:
+
+```text
+gitty.exe --clone "https://example.com/team/project.git" "D:\Projects\Project"
+gitty clone "git@example.com:team/project.git" "D:\Projects\Project"
+```
+
+`--clone=<REMOTE>` is also accepted. Relative target paths are resolved from
+the current working directory. Clone and repository requests are forwarded to
+the running window when Gitty is already open.
+
+---
+
 ## Git LFS
 
 Gitty bundles the `git-lfs` executable in its desktop installers and checks it