Port to Devenv

This will allow us to use in-project MySQL database instance.

- Started with `nix flake init --template github:cachix/devenv` as per https://devenv.sh/guides/using-with-flakes/
- Using devenv-nixpkgs https://devenv.sh/blog/2024/03/20/devenv-10-rewrite-in-rust/#devenv-nixpkgs
- Remove flake-compat as we switched to `use flake`.

.envrc

@@ -1,2 +1,10 @@
-use nix
-watch_file flake.nix flake.lock
+if ! has nix_direnv_version || ! nix_direnv_version 2.2.1; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/2.2.1/direnvrc" "sha256-zelF0vLbEl5uaqrfIzbgNzJWGmLzCmYAkInj/LNxvKs="
+fi
+
+watch_file flake.nix
+watch_file flake.lock
+if ! use flake . --no-pure-eval
+then
+  echo "devenv could not be built. The devenv environment was not loaded. Make the necessary changes to devenv.nix and hit enter to try again." >&2
+fi

.github/workflows/main.yaml

@@ -22,27 +22,27 @@ jobs:
         echo "sha_short=$(git rev-parse --short HEAD)" >> "$GITHUB_OUTPUT"
 
     - name: Install dependencies
-      run: nix-shell --run 'composer install --no-interaction'
+      run: nix shell -c composer install --no-interaction
 
     - name: Check code using Nette code checker
-      run: nix-shell --run 'code-checker -d app'
+      run: nix shell -c code-checker -d app
 
     - name: Lint coding style
-      run: nix-shell --run 'composer run-script cs'
+      run: nix shell -c composer run-script cs
 
     - name: Run static analysis
-      run: nix-shell --run 'composer run-script phpstan'
+      run: nix shell -c composer run-script phpstan
 
     - name: Lint source code
-      run: nix-shell --run 'composer run-script lint'
+      run: nix shell -c composer run-script lint
 
     - name: Run tests
       run: |
         cp .github/workflows/private.neon app/Config/private.neon
-        nix-shell --run 'composer test'
+        nix shell -c composer test
 
     - name: Build a zipball
-      run: nix-shell --run 'npm run dist "entries-${{ steps.vars.outputs.sha_short }}.zip"'
+      run: nix shell -c npm run dist "entries-${{ steps.vars.outputs.sha_short }}.zip"
 
     - name: Upload the zipball to GitHub
       uses: actions/upload-artifact@v4

.gitignore

@@ -12,3 +12,4 @@ phpstan.neon
 /.parcel-cache/
 
 /.direnv/
+/.devenv/