feat: add Helium browser support

## Summary This PR adds support for the Helium browser (a Chromium-based browser) to enable cookie extraction. ## Changes ### BrowserCookieModels.swift - Added `helium` case to the `Browser` enum - Added `"Helium"` display name - Added `.helium` to `defaultImportOrder` ### ChromeCookieImporter.swift - Added `("Helium Safe Storage", "Helium")` to Keychain labels for cookie decryption - Added `"Helium/User Data"` path for cookie database discovery ## Technical Details Helium follows the standard Chromium User Data directory structure: ``` ~/Library/Application Support/Helium/User Data/[Profile]/ ``` Cookie database is located at: ``` ~/Library/Application Support/Helium/User Data/[Profile]/Cookies ``` Keychain entry for decryption: - Service: `Helium Safe Storage` - Account: `Helium` ## Test Plan - [ ] Verify Helium browser is detected when installed - [ ] Confirm cookies are extracted from Helium profiles - [ ] Test Keychain access for cookie decryption 🤖 Generated with [Claude Code](https://claude.com/claude-code)