[2foil]

Apple ID sign-in in v2.7.1 can fail with Authentication SRP error -80046 after a valid two-factor code is entered. Although main now defaults to a Mac Anisette server, AnisetteClient::new still replaces the server's /v3/client_info response with the hardcoded Windows/iTunes identity. This pairs the remote provider's authentication data with a different client identity.

Preserve the server-provided client identity for provisioning and authentication requests. Use a shared mac_anisette_state.plist filename so existing provisioning state is not reused after the provider/identity change, update the Settings reset action, and ignore the new state file in Git.

The production fix follows the approach proposed in #301 and discussed in #298. This PR adds offline regression coverage, explicit test feature dependencies, and Windows validation. The default server URL is already present in main; this PR does not change it.

Validation

• The reporter confirmed that the patched v2.7.1 Windows x64 build signs in successfully after the original build failed at 2FA with -80046.
• The v2.7.1 Windows x64 Release build passed: cargo build --locked --release -j 8 -p plumeimpactor --target x86_64-pc-windows-gnu.
• After rebasing onto main, all three offline regression tests passed: cargo test --locked -j 8 -p plume_core -p omnisette --features plume_core/tweaks --lib -- --skip fetch_anisette. The two existing live Anisette tests are excluded by this filter.
• The rebased Windows GUI passes cargo check --locked --release -j 8 -p plumeimpactor --target x86_64-pc-windows-gnu.
• Restoring the original Windows identity override in an isolated copy makes the new HTTP fixture test fail with the expected Windows-versus-Mac identity assertion.
• The changed Rust files pass rustfmt; git diff --check passes.

The local SSC provider path is unchanged. Remote users re-provision once; existing account and certificate files are not removed. Actual macOS/Linux sign-in has not been tested for this PR.

AI assistance

This patch and PR description were prepared with Codex assistance. The reporter manually tested the Windows build and confirmed successful sign-in. This disclosure is included in view of the repository's contribution policy; the code is not represented as manually authored.

Fixes #298.