XY-1340 Restore deterministic canonical formatting and style-gate authority

[acgxv]

Summary

• pin the Rust formatter toolchain and restore the mechanical formatting baseline
• remove Vstyle from blocking/fixing aggregates and retain a governed read-only audit
• add provenance, baseline/delta, task-graph tests, and command authority documentation

Validation

• cargo make test-gate-contract
• cargo make audit-vstyle-rust
• cargo make fmt-rust-check
• cargo make fmt-toml-check
• cargo make lint-rust
• cargo make test
• DEVELOPER_DIR=/Applications/Xcode-beta.app/Contents/Developer RUSTC_WRAPPER= cargo make check

Independent visible review: NO_BLOCKING_FINDINGS for candidate fingerprint 0690fa108f140399d02af294e3d79ae7530f3793dcc6df541abe4d5dae62b7d0.