ci(rust): convert rust-ci.yml to thin wrapper (standards#174)

Replaces the per-repo `rust-ci.yml` copy with a 5-line wrapper invoking
the shared reusable workflow in `hyperpolymath/standards` (PR #174).

Pinned to PR #174's HEAD SHA `4fdf4314b4ab54269adbaff10e30e483b5e86845`; will resolve to standards/main
once #174 merges.

Estate audit found ~87 rust-ci.yml copies across the estate; this is
one of them. The reusable provides identical cargo check/clippy/fmt/test
behaviour with opt-in `enable_audit` + `enable_coverage` inputs.

Pattern precedent: standards#168 (governance-reusable) + downstream
wrappers absolute-zero#41 + tma-mark2#41.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/rust-ci.yml

@@ -1,53 +1,20 @@
-# SPDX-License-Identifier: MPL-2.0-or-later
+# SPDX-License-Identifier: MPL-2.0
+# Rust CI — thin wrapper calling the shared estate reusable in
+# hyperpolymath/standards. Configure once, propagate everywhere.
+# See: docs/CI-REUSABLE-WORKFLOWS.adoc in standards.
 name: Rust CI
-on: [push, pull_request]
-env:
-  CARGO_TERM_COLOR: always
-  RUSTFLAGS: -Dwarnings
 
-jobs:
-  test:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v6.0.2
-      - uses: dtolnay/rust-toolchain@stable
-        with:
-          components: rustfmt, clippy
-      - uses: Swatinem/rust-cache@v2
-      
-      - name: Check formatting
-        run: cargo fmt --all -- --check
-      
-      - name: Clippy lints
-        run: cargo clippy --all-targets --all-features -- -D warnings
-      
-      - name: Run tests
-        run: cargo test --all-features
-      
-      - name: Build release
-        run: cargo build --release
+on:
+  push:
+    branches: [main, master]
+  pull_request:
 
-  security:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v6.0.2
-      - uses: dtolnay/rust-toolchain@stable
-      - name: Install cargo-audit
-        run: cargo install cargo-audit
-      - name: Security audit
-        run: cargo audit
-      - name: Check for outdated deps
-        run: cargo install cargo-outdated && cargo outdated --exit-code 1 || true
+permissions:
+  contents: read
 
-  coverage:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v6.0.2
-      - uses: dtolnay/rust-toolchain@stable
-      - name: Install tarpaulin
-        run: cargo install cargo-tarpaulin
-      - name: Generate coverage
-        run: cargo tarpaulin --out Xml
-      - uses: codecov/codecov-action@v6
-        with:
-          files: cobertura.xml
+jobs:
+  rust-ci:
+    uses: hyperpolymath/standards/.github/workflows/rust-ci-reusable.yml@4fdf4314b4ab54269adbaff10e30e483b5e86845
+    with:
+      enable_audit: true
+      enable_coverage: true