feat: full Rust rewrite (17-crate Cargo workspace)

.gitattributes

@@ -9,3 +9,8 @@
 # test/config-schema-generated.test.ts; pin LF so Windows autocrlf
 # checkouts do not produce spurious drift failures.
 config/schema/config.schema.json text eol=lf
+crates/testkit/goldens/** -text
+crates/**/*.rs text eol=lf
+Cargo.toml text eol=lf
+crates/**/Cargo.toml text eol=lf
+Cargo.lock text eol=lf

.github/workflows/rust.yml

@@ -0,0 +1,52 @@
+name: Rust
+
+on:
+  push:
+    branches: [main]
+    paths: ["crates/**", "Cargo.toml", "Cargo.lock", ".github/workflows/rust.yml"]
+  pull_request:
+    branches: [main]
+    paths: ["crates/**", "Cargo.toml", "Cargo.lock", ".github/workflows/rust.yml"]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: rust-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    name: Test on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # stable
+        with:
+          toolchain: "1.96.0"
+          components: clippy, rustfmt
+
+      - name: Cache cargo
+        uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809 # v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: cargo-${{ matrix.os }}-${{ hashFiles('Cargo.lock') }}
+
+      - name: Check
+        run: cargo check --workspace --all-targets
+
+      - name: Clippy
+        run: cargo clippy --workspace --all-targets -- -D warnings
+
+      - name: Test
+        run: cargo test --workspace

.gitignore

@@ -35,3 +35,6 @@ test-results.md
 
 # OMC session scratch (never publish)
 .omc/
+
+# Rust
+/target