build: replace run.sh with a Makefile

Provide make targets for building, running, testing, linting, generating
sqlc code, and managing database migrations. Remove the run.sh script.

Makefile

@@ -0,0 +1,94 @@
+# Makefile for Chirpy.
+
+BINARY_NAME ?= chirpy
+BIN_DIR     ?= bin
+BINARY      := $(BIN_DIR)/$(BINARY_NAME)
+
+# Prefer tools installed into GOBIN, falling back to PATH.
+GOBIN_DIR       := $(shell go env GOPATH)/bin
+GOOSE           ?= $(if $(wildcard $(GOBIN_DIR)/goose),$(GOBIN_DIR)/goose,goose)
+SQLC            ?= $(if $(wildcard $(GOBIN_DIR)/sqlc),$(GOBIN_DIR)/sqlc,sqlc)
+GOLANGCI_LINT   ?= $(if $(wildcard $(GOBIN_DIR)/golangci-lint),$(GOBIN_DIR)/golangci-lint,golangci-lint)
+
+# Load local configuration from .env when present. Note: values in .env must
+# not contain a bare '#' character, as Make would treat it as a comment.
+DB_URL ?= postgres://postgres:postgres@localhost:5432/chirpy?sslmode=disable
+-include .env
+export
+
+GO_SOURCES := $(shell find . -name '*.go' -not -path './bin/*' -not -path './internal/database/*')
+
+.DEFAULT_GOAL := help
+
+.PHONY: help build run dev test test-race vet fmt fmt-check tidy lint \
+        generate clean migrate-up migrate-down migrate-status migrate-reset \
+        install-tools check
+
+help: ## Show this help message
+	@grep -hE '^[a-zA-Z_-]+:.*?## ' $(MAKEFILE_LIST) | awk 'BEGIN {FS = ":.*?## "}; {printf "  \033[36m%-18s\033[0m %s\n", $$1, $$2}'
+
+build: ## Compile the server binary into $(BIN_DIR)
+	@mkdir -p $(BIN_DIR)
+	go build -o $(BINARY) .
+
+run: build ## Build and run the server
+	./$(BINARY)
+
+dev: ## Run the server with the race detector enabled
+	go run -race .
+
+test: ## Run all tests
+	go test ./...
+
+test-race: ## Run all tests with the race detector
+	go test -race ./...
+
+vet: ## Run go vet
+	go vet ./...
+
+fmt: ## Format all Go source files
+	gofmt -s -w $(GO_SOURCES)
+
+fmt-check: ## Verify Go sources are formatted
+	@unformatted="$$(gofmt -l $(GO_SOURCES))"; \
+	if [ -n "$$unformatted" ]; then \
+		echo "The following files are not formatted:"; \
+		echo "$$unformatted"; \
+		exit 1; \
+	fi
+
+tidy: ## Tidy module dependencies
+	go mod tidy
+
+lint: ## Run golangci-lint if installed
+	@if ! command -v $(GOLANGCI_LINT) >/dev/null 2>&1; then \
+		echo "golangci-lint is not installed. Run 'make install-tools' to install it."; \
+		exit 1; \
+	fi
+	$(GOLANGCI_LINT) run ./...
+
+generate: ## Regenerate the sqlc database query code
+	$(SQLC) generate
+
+clean: ## Remove build artifacts
+	rm -rf $(BIN_DIR)
+
+migrate-up: ## Apply pending database migrations
+	$(GOOSE) -dir sql/schema postgres "$(DB_URL)" up
+
+migrate-down: ## Roll back the most recent migration
+	$(GOOSE) -dir sql/schema postgres "$(DB_URL)" down
+
+migrate-status: ## Show the current migration status
+	$(GOOSE) -dir sql/schema postgres "$(DB_URL)" status
+
+migrate-reset: ## Roll back all migrations and re-apply them
+	$(GOOSE) -dir sql/schema postgres "$(DB_URL)" down-to 0
+	$(GOOSE) -dir sql/schema postgres "$(DB_URL)" up
+
+install-tools: ## Install dev tools (goose, sqlc, golangci-lint)
+	go install github.com/pressly/goose/v3/cmd/goose@latest
+	go install github.com/sqlc-dev/sqlc/cmd/sqlc@latest
+	go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+
+check: fmt-check vet test ## Run formatting, vet, and test checks

run.sh

@@ -1,7 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-cd "$(dirname "$0")"
-
-go build -o ./bin/chirpy .
-./bin/chirpy