ci: add step to install devenv in CI workflow

Install devenv using nix profile install nixpkgs#devenv to enable
running bun commands within devenv shell environment.

Author: MBanucu

.github/workflows/ci.yml

@@ -76,6 +76,8 @@ jobs:
         uses: DeterminateSystems/magic-nix-cache-action@v13
         with:
           use-flakehub: false
+      - name: Install devenv
+        run: nix profile install nixpkgs#devenv
       - name: Cache Bun dependencies
         uses: actions/cache@v5
         with:
@@ -87,4 +89,4 @@ jobs:
         run: devenv shell -- bun build:prod
 
       - name: Quality checks (Devenv shell)
-        run: devenv shell -- bun ${{matrix.quality}}
+        run: devenv shell -- bun ${{matrix.quality}}