Remote /prove endpoint + desktop Linux WebKit fix | Notes | Skill Issue Dev

For users on phones or low-end laptops, generating a Groth16 proof in 1.5s is still 1.5s of dead UI. Added a /prove endpoint on vanta-explorer that takes a witness, runs the prover server-side, and returns the 128-byte proof. Trust trade-off documented in the desktop app — server sees the witness, but only the user sees the resulting note keys.

Same commit fixes the Linux WebKit build for vanta-desktop. Tauri’s WebView2 default works on Windows and macOS but Linux needs WEBKIT_DISABLE_COMPOSITING_MODE=1 for the proof-modal animation to not crash on AMD GPUs. Three hours of bisecting to find that one line.