Add Nix flake development environment with direnv

flake.nix

@@ -19,16 +19,32 @@
             cargo
             rustfmt
             clippy
-            
+	    cargo-watch
+
             # C build tools (for your linker issue)
             gcc
             binutils
             pkg-config
+            
+            # OpenSSL for crypto dependencies
+            openssl
+            openssl.dev
+            
+            # PostgreSQL for sqlx
+            postgresql
+	    sqlx-cli
+            
+            # Protocol Buffers compiler for gRPC
+            protobuf
           ];
 
           shellHook = ''
+            export PKG_CONFIG_PATH="${pkgs.openssl.dev}/lib/pkgconfig:$PKG_CONFIG_PATH"
+            export OPENSSL_DIR="${pkgs.openssl.dev}"
+            export OPENSSL_LIB_DIR="${pkgs.openssl.out}/lib"
+            export OPENSSL_INCLUDE_DIR="${pkgs.openssl.dev}/include"
             echo "🦀 Rust development environment loaded"
-            echo "Run 'cargo check' to verify everything works"
+            echo "OpenSSL and PostgreSQL available"
           '';
         };
       }