feat(testing): add full integration test suite

This commit introduces a comprehensive integration test suite for the pgsql-broker.

The test suite includes:
- A Docker/Podman environment for running a PostgreSQL database, managed via a .
- Integration tests that cover the broker's lifecycle, including job creation, execution, and instance management.
- A GitHub Actions workflow to automate the execution of all tests on push and pull requests.
- A dedicated test configuration file () and helper test files.

refactor(worker): fix job processing transaction
- The worker's job processing now uses a single transaction to fetch and run a job, resolving a race condition where jobs were not in the 'running' state when being executed.
- The broker's database instance registration is now more robust, handling cases where another instance is already active.

The Makefile has been significantly updated to orchestrate the entire test flow, including setting up the database, starting/stopping the broker, and running unit and integration tests separately.

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all build clean test install deps help
+.PHONY: all build clean test test-all test-integration-go test-unit-go test-connection schema-install broker-start broker-stop install deps help
 
 # Build variables
 BINARY_NAME=pgsql-broker
@@ -10,7 +10,7 @@ LDFLAGS=-w -s
 
 # Version information
 VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
-BUILD_TIME=$(shell date -u '+%Y-%m-%d_%H:%M:%S')
+BUILD_TIME=$(shell date -u '+2026-01-02_19:58:30')
 COMMIT=$(shell git rev-parse --short HEAD 2>/dev/null || echo "unknown")
 
 # Inject version info
@@ -36,9 +36,47 @@ deps: ## Download dependencies
 	@$(GO) mod tidy
 	@echo "Dependencies ready"
 
-test: ## Run tests
-	@echo "Running tests..."
-	@$(GO) test -v -race -cover ./...
+# Main test target to run everything
+test-local-unit: deps ## Run local unit tests
+	@echo "Running local unit tests..."
+	@$(GO) test -v -race -cover $(shell $(GO) list ./... | grep -v /tests/integration)
+
+test-all: test-teardown test-setup test-connection schema-install broker-start test-local-unit test-integration-go broker-stop test-teardown ## Run all unit and integration tests
+
+test-connection: deps ## Test database connection with retry
+	@echo "Testing database connection..."
+	@$(GO) test -v ./tests/integration/connection_test.go
+
+schema-install: build ## Install database schema using the broker CLI
+	@echo "Installing database schema..."
+	@$(BIN_DIR)/$(BINARY_NAME) install --config broker.test.yaml
+
+test-setup: build ## Start test environment (docker-compose)
+	@echo "Starting test environment..."
+	@podman-compose -f tests/docker-compose.yml up -d
+
+test-teardown: ## Stop test environment (docker-compose)
+	@echo "Stopping test environment..."
+	@podman-compose -f tests/docker-compose.yml down -v --rmi all
+	@sleep 5 # Give Docker time to release resources
+
+broker-start: build ## Start the broker in the background
+	@echo "Starting broker..."
+	@setsid $(BIN_DIR)/$(BINARY_NAME) start --config broker.test.yaml > broker.log 2>&1 < /dev/null & echo $$! > broker.pid
+	@sleep 5 # Give the broker a moment to start
+
+broker-stop: ## Stop the broker
+	@echo "Stopping broker..."
+	@if [ -f broker.pid ]; then \
+		kill -15 -- -$$(cat broker.pid); \
+		rm broker.pid; \
+	else \
+		echo "broker.pid not found, broker might not be running."; \
+	fi
+
+test-integration-go: ## Run Go integration tests
+	@echo "Running Go integration tests..."
+	@$(GO) test -v ./tests/integration/...
 
 install: build ## Install the binary to GOPATH/bin
 	@echo "Installing to GOPATH/bin..."
@@ -61,10 +99,10 @@ vet: ## Run go vet
 
 lint: ## Run golangci-lint (if installed)
 	@if command -v golangci-lint >/dev/null 2>&1; then \
-		echo "Running golangci-lint..."; \
-		golangci-lint run ./...; \
+		 echo "Running golangci-lint..."; \
+		 golangci-lint run ./...; \
 	else \
-		echo "golangci-lint not installed, skipping"; \
+		 echo "golangci-lint not installed, skipping"; \
 	fi
 
 sql-install: build ## Install SQL tables and procedures using broker CLI
@@ -84,5 +122,4 @@ sql-install-manual: ## Install SQL tables and procedures manually via psql
 help: ## Show this help message
 	@echo "Usage: make [target]"
 	@echo ""
-	@echo "Targets:"
-	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "  %-15s %s\n", $$1, $$2}'
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "  %-15s %s\n", $$1, $$2}'