GitHub Workflow: deprecate prettier and rustfmt and use "nix fmt" instead

.github/workflows/qc.yaml

@@ -13,14 +13,6 @@ permissions:
   contents: read
 
 jobs:
-  prettier:
-    runs-on: ubicloud-standard-2-ubuntu-2204
-    steps:
-      - uses: actions/checkout@v5
-      - uses: actionsx/prettier@v3
-        with:
-          args: --check .
-
   shellcheck:
     name: Shellcheck
     runs-on: ubicloud-standard-2-ubuntu-2204
@@ -30,28 +22,16 @@ jobs:
         uses: ludeeus/action-shellcheck@master
 
   rustfmt:
-    name: Rust code formatting
+    name: Code Formatting
     runs-on: ubicloud-standard-2-ubuntu-2204
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/cache@v4
-        with:
-          path: |
-            ~/.cargo/bin/
-            ~/.cargo/registry/index/
-            ~/.cargo/registry/cache/
-            ~/.cargo/git/db/
-            target/
-          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
-      - name: Install nightly toolchain
-        run: |
-          rustup toolchain install nightly
-          rustup override set nightly
-      - run: rustup component add rustfmt
-      - name: Run Cargo Fmt
-        run: cargo fmt --all --check
-      - name: Run Rust Markdown code block Formatting Script
-        run: bash format_rust_code.sh --mode check
+      - uses: cachix/install-nix-action@v30
+        with: nix_path: nixpkgs=channel:nixos-26.05
+      - uses: cachix/cachix-action@v15
+        with: name: rosenpass authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+      - name: run nix format
+        run: nix fmt -- --fail-on-change
 
   cargo-bench:
     runs-on: ubicloud-standard-2-ubuntu-2204