chore: cut provekit-baseline-std + provekit-baseline-rust-std

Hand-authored stdlib contract baselines (must()/contract(), same API as
the deleted .invariant DSL) in a central advisory catalog: the .invariant
disease one tier out. We don't author contracts for code we don't own;
std's contracts come from std's own lifted forms or the language team's
.proof, or we refuse. Out of scope per CODE-VS-DICTIONARY.md (T-confirmed).

Zero external dependents; no Makefile/CI wiring. Workspace resolves clean.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: TSavo

implementations/rust/Cargo.lock

@@ -15,7 +15,6 @@ members = [
     "provekit-ir-compiler-lean",
     "provekit-verifier",
     "provekit-self-contracts",
-    "provekit-baseline-rust-std",
     "libprovekit",
     "libprovekit-rpc",
     "provekit-cli",
@@ -43,7 +42,6 @@ members = [
     "provekit-build",
     "examples/build_script_demo",
     "provekit-linkerd",
-    "provekit-baseline-std",
     "../../menagerie/bug-zoo",
     "../../menagerie/bridgeworks",
     "../../menagerie/supply-chain-rails",