Adopt noir-rs v1.0.0-beta.19 (barretenberg-rs migration) across mopro

[moven0831]

Summary

zkmopro/noir-rs#37 upgraded noir-rs to v1.0.0-beta.19 and moved from the custom bb/ crate to the official barretenberg-rs. The PR explicitly defers mopro-side updates. This issue tracks them.

Tasks

• Upgrade the noir-rs pin in cli/src/init/noir.rs — bump off v1.0.0-beta.8-3 and drop the removed android-compat feature.
• Regenerate noir test fixtures (noir_multiplier2.json / .srs / .vk) under nargo 1.0.0-beta.19 — ACIR format, SRS sizing, and proof layout all changed.
• Update noir-related app templates (iOS ContentView.swift, Android NoirComponent.kt, Flutter, RN) and verify a fresh mopro init --adapter noir builds and runs end-to-end on device.
• Update docs — docs/docs/adapters/noir.md (version strings, drop x86_64-apple-ios, drop aztec-packages reference) and the May 2025 noir integration blog post.
• Update CI — bump nargo to 1.0.0-beta.19 in .github/workflows/build-and-test.yml and drop x86_64-apple-ios from the matrix.

References

• noir-rs PR: Upgrade to noir v1.0.0-beta.19 and adopt official barretenberg-rs noir-rs#37
• noir-lang release: https://github.com/noir-lang/noir/releases/tag/v1.0.0-beta.19
• Related: [Noir] separating proof bytes and public signals bytes #422, rust-witness fails to compile for iOS targets if using both Circom and Noir #551