feat(legal): load in-app legal docs from GitHub at runtime

[CharlVS]

Summary

• add markdown legal documents under assets/legal/ for the EULA, Terms of Service, Privacy Notice, and KYC policy
• replace the hardcoded EULA/ToS disclaimer content with a shared markdown viewer backed by an app-side legal documents repository
• load bundled or cached content first, then refresh from the GitHub Contents API (GLEECBTC/gleec-wallet@main) so legal copy can be updated without shipping a new app release
• add top-level Privacy Notice and KYC Policy entries in Settings while keeping onboarding acceptance scoped to the EULA and Terms
• refresh the bundled KYC markdown from the supplied website export and keep the legal-doc UI behavior consistent across onboarding and settings
• preserve existing dialog close behavior, tappable markdown links, and integration keys used by the wallet onboarding flows
• no SDK changes are included in this PR

Validation

• dart format on the changed Dart files
• focused flutter analyze on the touched app files for legal document loading, routing, settings, and onboarding dialogs

Testing Instructions

1. Navigate to https://walletrc--pull-3427-merge-hd0y6g75.web.app/
2. Sign out, click Connect Wallet, then start either the Create Wallet or Import Wallet flow.
3. Open EULA and Terms & Conditions from the acceptance checkbox area.
4. Verify both documents render as scrollable markdown, links are tappable, and Close dismisses the dialog.
5. Open Settings -> Privacy Notice on desktop and mobile layouts.
6. Open Settings -> KYC Policy on desktop and mobile layouts.
7. Verify both settings pages render the expected markdown content and remain readable when the GitHub request fails by falling back to bundled content.
8. Verify refreshed content can update from main without a new app release.

[github-actions]

Visit the preview URL for this PR (updated for commit 0634b87):

https://walletrc--pull-3427-merge-hd0y6g75.web.app

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