refactor: rewrite project from Rust to Go

- Replace Axum with Chi router
- Replace sqlx with pgx for PostgreSQL
- Replace tonic/prost with grpc-go
- Replace tracing with zerolog
- Update flake.nix for Go build with protoc generation
- Preserve all existing endpoints and functionality

Stack: Chi, pgx, grpc-go, zerolog, yaml.v3

flake.nix

@@ -33,16 +33,39 @@
             src = ./.;
             hooks = {
               nixfmt.enable = true;
-              rustfmt.enable = true;
+              gofmt.enable = true;
             };
           };
 
-          music-agregator = pkgs.rustPlatform.buildRustPackage {
+          music-agregator = pkgs.buildGoModule {
             pname = "music-agregator";
             version = "0.1.0";
             src = ./.;
-            cargoLock.lockFile = ./Cargo.lock;
-            nativeBuildInputs = [ pkgs.protobuf ];
+            vendorHash = "sha256-gad5/pLGWyU45QiEvZJ8xEKNy4K2p5OykKE0nykzh8w=";
+
+            nativeBuildInputs = [
+              pkgs.protobuf
+              pkgs.protoc-gen-go
+              pkgs.protoc-gen-go-grpc
+            ];
+
+            preBuild = ''
+              export HOME=$(mktemp -d)
+              mkdir -p pkg/metadatapb/metadata/v1
+              ${pkgs.protobuf}/bin/protoc \
+                --plugin=protoc-gen-go=${pkgs.protoc-gen-go}/bin/protoc-gen-go \
+                --plugin=protoc-gen-go-grpc=${pkgs.protoc-gen-go-grpc}/bin/protoc-gen-go-grpc \
+                --proto_path=proto \
+                --go_out=pkg/metadatapb --go_opt=paths=source_relative \
+                --go-grpc_out=pkg/metadatapb --go-grpc_opt=paths=source_relative \
+                proto/metadata/v1/metadata.proto
+            '';
+
+            subPackages = [ "cmd/server" ];
+
+            postInstall = ''
+              mv $out/bin/server $out/bin/music-agregator
+            '';
           };
         in
         {
@@ -65,11 +88,13 @@
               gitleaks
               plantuml
               protobuf
+              protoc-gen-go
+              protoc-gen-go-grpc
 
-              rustc
-              cargo
-              rustfmt
-              clippy
+              go
+              gopls
+              gotools
+              go-tools
             ];
           };
         };