Rebrand to Checker App

[juliangruber]

• Design (Lumen)
• Implement design
• Switch from @filecoin-station/core to @checkernetwork/node #2049
• Rename Station Desktop -> Checker
• Rename repo to /app
• Migrate InfluxDB (out of scope)
• Migrate Plausible (out of scope)
• Update docs.filstation.app
  • Seed phrase key is now "checker-wallet-0x'
• Migrate wallet screening service (out of scope)
• Logos
  • In app
  • In tray
  • application icon
• Onboarding text
• TOS (currently links to https://pl-strflt.notion.site/Station-Terms-Conditions-e97da76bb89f49e280c2897aebe4c41f)
• Add download page to checker.network
• Update repo description text