Update QuickSSH standalone icon set

[Vaso73]

Summary

• Replace the old QuickSSH icon assets with a new standalone liquid/glow icon identity.
• Use a blue default icon for normal results.
• Keep green and red icons for valid/success and remove/error states.
• Remove unused color variants that are no longer referenced.

Validation

• Runtime tested manually in Flow Launcher portable install:

  • ssh profiles
  • ssh profiles remove
  • green profile entries
  • red remove entries

• Built locally:

  dotnet build Flow.Launcher.Plugin.QuickSSH.csproj --configuration Release

Notes

• No plugin ID/GUID changes.
• No command behavior changes.
• No version bump in this PR; release bump should be separate after merge.