fix(ios): support None as an SSH tunnel auth method

[datlechin]

Summary

Adds iOS parity for the None SSH tunnel auth method.

The None method (for hosts like Tailscale SSH that handle authentication themselves) shipped on macOS in v0.59.0 (#1907, #1909). The iOS app models SSH config with a separate type that was never taught the case, so a macOS connection using None, once synced to iOS, silently decoded to Password and then failed to connect with a misleading "No SSH password provided."

Changes

iOS now honors None SSH tunnels. iOS uses libssh2 too, so this is real support rather than a clean error:

• SSHConfiguration (TableProModels): add the .none case and decode "none" / "None".
• iOS SSHTunnel: add authenticateNone, mirroring the macOS NoneAuthenticator sequence (libssh2_userauth_list then libssh2_userauth_authenticated).
• iOS SSHTunnelFactory: dispatch .none.
• IOSConnectionImportService: map "none" when importing a .tablepro file.

Tests:

• Extract the macOS None form gate into SSHAuthMethod.supportsTwoFactorAuthentication (same behavior, now testable) and cover it in TableProTests.
• iOS model decode tests for .none: the macOS and lowercase raw values, an encode/decode round trip, and the unknown-value fallback to Password.

Testing

• swift test --filter SSHConfigurationTests: 4/4 pass.
• swiftlint lint --strict: clean on changed in-scope files.

Notes

• The macOS feature already shipped, so issue Please add “None” as an authentication method for SSH tunnels #1912 has a reply pointing the reporter to v0.59.0, plus the Tailscale check-mode caveat (that mode rejects none).
• Out of scope: adding None to the iOS form's auth picker (it is curated to Password / Private Key), and the pre-existing iOS to macOS raw-value casing question.

Ref #1912

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Render None as None in the iOS tunnel summary

When a synced or imported connection uses this newly supported .none value, ConnectionInfoView.swift:107 treats every non-password method as "Private Key". The tunnel can now authenticate successfully without a key, but its connection details misleadingly report Private Key; add an explicit None display case (and ideally handle the other enum cases rather than collapsing them).

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