Make the About page's footnote plain: copyright, Made in the UK, open source

Replace the Bad Bundle logo and "free and open since 2024 ✌️" at the bottom of the About page with a plain footnote of three lines:

• Copyright 2026 Bad Bundle Limited
• Made in the UK
• Open source

The last line is there because Vault is open source, and it says just that. GPS carries the same footnote without it, because GPS isn't open source (GPS-2). The two should read and look the same.

Style, shared with GPS: plain text, centred, .caption2, .secondary, with no row background. No icon, no logo and no emoji. It's a footnote, so keep it modest and small.

Where: mastheadSection in VaultAboutView (Vault/Sources/VaultiOS/Views/Settings/VaultAboutView.swift).

• Remove the bad-bundle-logo image and the "free and open since 2024 ✌️" line.
• Nothing else uses the logo, so delete bad-bundle-logo.imageset from Vault/Sources/VaultFeed/Resources/Media.xcassets too.
• The version line stays below the footnote, as it is now below the tagline.

Tests: re-record the VaultAboutViewSnapshotTests baseline (layout.1.png), and say in the PR body that the logo and the emoji are gone and the footnote has replaced the tagline.