chore: pin Rust toolchain to 1.94.0 for consistent rustfmt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: skeptomai

.github/workflows/ci.yml

@@ -13,9 +13,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Install Rust stable
-        uses: dtolnay/rust-toolchain@stable
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@master
         with:
+          toolchain: "1.94.0"
           components: clippy, rustfmt
 
       - name: Cache cargo

rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "1.94.0"
+components = ["rustfmt", "clippy"]