Add LOOS Monokai theme

[ddryo]

Adds LOOS Monokai, a customized Monokai dark theme for Zed
(refined syntax, diff, diagnostics, and terminal colors).

• Repository: https://github.com/ddryo/loos-monokai
• Extension ID: loos-monokai-theme
• Path: zed (monorepo — the Zed extension lives in the zed/ subdirectory)
• License: MIT

Checklist

• Tested locally as a dev extension
• Added as a Git submodule via HTTPS
• Added an entry to extensions.toml and ran pnpm sort-extensions
• An accepted license (MIT) is included at the extension path

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[ddryo]

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