Add text object font support

[shipilovden]

Summary

• add a text_font field for text objects, including serialisation, protocol version bump, and a small regression test
• add text font selection to the object editor and render text objects with the selected font in the native and web clients
• bundle the text font pack plus emoji font resources, and serve gui_client.data without content-encoding for the web client path

Details

• text objects now keep an optional font name with Default as the fallback
• the editor scans resources/fonts and exposes the available font names in a combo box
• GUIClient loads per-font face sets on demand and reuses them when rendering text meshes
• the emscripten client now prefers NotoColorEmoji_WindowsCompatible.ttf for emoji rendering while keeping Roboto as a fallback for UI text

Verification

• git diff --check
• git diff --cached --check
• full project build was not run in this environment

[Ono-Sendai]

How big is the text font pack (in bytes)?
The reason I ask is that keeping the download small and fast for the web is very important.

What is the licence on the fonts?