fix: bundle and load own font

[OpenSauce]

fixes #229

There seems to be some issues with Iced and default fonts, depending on your system. So I'm just bundling in the font file and setting it.

[Copilot]

Pull request overview

This PR aims to fix missing UI text on systems without the expected default fonts by bundling a font asset in rustortion-ui and configuring the standalone Iced app to load and use it by default.

Changes:

• Add a rustortion_ui::font module exposing embedded font bytes and a corresponding iced::Font.
• Configure the standalone GUI (iced::application) to load the embedded font and set it as the default font.
• Adjust tuner dialog text rendering by removing explicit monospace font usage for the cents indicator.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 3 comments.

File	Description
rustortion-ui/src/lib.rs	Exposes the new font module from the UI crate.
rustortion-ui/src/font.rs	Defines embedded font bytes and the default iced::Font name to use.
rustortion-standalone/src/gui/mod.rs	Registers the embedded font with Iced and sets it as the default font for the standalone app.
rustortion-standalone/src/gui/components/dialogs/tuner.rs	Removes explicit monospace font usage in the tuner’s cents indicator text.

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