Add FXIOS-16205 Add new Nova tokens to the existing ThemeColourPallete

[rilury]

📜 Tickets

Jira ticket
Github issue

💡 Description

This PR consolidates Nova and current themes into a single ThemeColourPalette (remove NovaThemeColourPalette) and wires Nova-only tokens: layerInverse/layerGlassTintNova/textToast (toast), iconPrivate (private badge), iconInverted (tab-tray Done checkmark). The current theme implementation is not impacted.

🎥 Demos

Before	After

Demo

📝 Checklist

• I filled in the ticket numbers and a description of my work
• I updated the PR name to follow our PR naming guidelines
• I ensured unit tests pass and wrote tests for new code
• If working on UI, I checked and implemented accessibility (Dynamic Text and VoiceOver)
• If adding telemetry, I read the data stewardship requirements and will request a data review
• If adding or modifying strings, I read the guidelines and will request a string review from l10n
• If needed, I updated documentation and added comments to complex code

[mobiletest-ci-bot]

	Messages
📖	Project coverage: 44.65%

🥇 Perfect PR size

Smaller PRs are easier to review. Thanks for making life easy for reviewers! ✨

💬 Description craftsman

Great PR description! Reviewers salute you 🫡

✅ Code coverage

• No new files detected so the coverage gate wasn't run.
• No modified files had significant enough changes for the coverage gate to run.

Client.app: Coverage: 43.51

File	Coverage
Toast.swift	81.59%	✅
TabTrayPanelSwipeTheme.swift	0.0%	⚠️
ButtonToast.swift	72.63%	✅
TabTrayViewController.swift	51.55%	✅
TabTrayPanelSwipePalette.swift	0.0%	⚠️

ToolbarKit: Coverage: 66.16

File	Coverage
ToolbarButton.swift	62.18%	✅

Generated by 🚫 Danger Swift against d3332ab

[thatswinnie]

I don't think we should make tokens optional - every theme should have a color value for every token available. Instead let's assign maybe a clear color to the ones not in use. And we should check which token to use based on the nova feature flag (which also makes it easier to clean the code up later).

[rilury]

Hey, @thatswinnie I updated the code. All tokens are now non-optional: Nova themes hold the real values, the others assign .clear to the Nova only tokens. Call sites pick via theme.isNova, which reflects the .novaDesign flag since the theme manager only returns a Nova theme when it's on.
I used isNova rather than reading the flag directly because some call sites (BrowserKit components) only receive a Theme and have no access to FeatureFlaggable. Thank you!