feat: Add installer for official Obsidian CLI

[yugal1107]

Fixes #5743

Summary

The official Arch Linux obsidian package (and the AUR obsidian-bin package) does not include the official Obsidian CLI binary (obsidian-cli). It only includes the Electron wrapper script.

This PR introduces omarchy install obsidian-cli, which downloads the latest official release, extracts the standalone obsidian-cli binary, and places it in ~/.local/bin/obsidian-cli.

How to test

1. Run omarchy install obsidian-cli
2. Verify with obsidian-cli --help (ensure the Obsidian GUI is running first).

[Copilot]

Copilot wasn't able to review any files in this pull request.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Copilot wasn't able to review any files in this pull request.

[mateuszkowalczyk]

I've noticed that it actually works out of the box for me, but in a kind of unexpected way, what I mean by that:

• if you run obsidian in the terminal, it will open Obsidian app
• but if you have the Obsidian app already running, it will open the CLI
• you still have to enable cli in app settings and it will tell you that it's unable to do this because of electron executable, but it starts working once you do that 🤔

I'm not sure if it's permanent behavior, but worth considering IMO. You could verify if it works like this on your side too.