feat: implement Epic 0 - Project Setup & Foundation

Implemented all 5 stories from Epic 0:

Story 0.1: Project Initialization
- Initialize Go module with path git.dcentral.systems/toolz/goplt
- Create complete directory structure (cmd/, internal/, pkg/, modules/, config/, etc.)
- Add comprehensive .gitignore for Go projects
- Create README.md with project overview and setup instructions

Story 0.2: Configuration Management System
- Define ConfigProvider interface in pkg/config
- Implement Viper-based configuration in internal/config
- Create configuration loader with environment support
- Add default, development, and production YAML config files

Story 0.3: Structured Logging System
- Define Logger interface in pkg/logger
- Implement Zap-based logger in internal/logger
- Add request ID middleware for Gin
- Create global logger export with convenience functions
- Support context-aware logging with request/user ID extraction

Story 0.4: CI/CD Pipeline
- Create GitHub Actions workflow for CI (test, lint, build, fmt)
- Add comprehensive Makefile with development commands
- Configure golangci-lint with reasonable defaults

Story 0.5: Dependency Injection and Bootstrap
- Create FX-based DI container in internal/di
- Implement provider functions for Config and Logger
- Create application entry point in cmd/platform/main.go
- Add lifecycle management with graceful shutdown

All acceptance criteria met:
- go build ./cmd/platform succeeds
- go test ./... runs successfully
- go mod verify passes
- Config loads from config/default.yaml
- Logger can be injected and used
- Application starts and shuts down gracefully

internal/di/container.go

@@ -0,0 +1,66 @@
+package di
+
+import (
+	"context"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"go.uber.org/fx"
+)
+
+// Container wraps the FX application and provides lifecycle management.
+type Container struct {
+	app *fx.App
+}
+
+// NewContainer creates a new DI container with the provided options.
+func NewContainer(opts ...fx.Option) *Container {
+	// Add core module
+	allOpts := []fx.Option{CoreModule()}
+	allOpts = append(allOpts, opts...)
+
+	app := fx.New(allOpts...)
+
+	return &Container{
+		app: app,
+	}
+}
+
+// Start starts the container and blocks until shutdown.
+func (c *Container) Start(ctx context.Context) error {
+	// Start the FX app
+	if err := c.app.Start(ctx); err != nil {
+		return err
+	}
+
+	// Wait for interrupt signal
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
+
+	// Block until signal received
+	<-sigChan
+
+	// Create shutdown context
+	shutdownCtx, cancel := context.WithTimeout(context.Background(), c.getShutdownTimeout())
+	defer cancel()
+
+	// Stop the FX app
+	if err := c.app.Stop(shutdownCtx); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Stop stops the container gracefully.
+func (c *Container) Stop(ctx context.Context) error {
+	return c.app.Stop(ctx)
+}
+
+// getShutdownTimeout returns the shutdown timeout duration.
+// Can be made configurable in the future.
+func (c *Container) getShutdownTimeout() time.Duration {
+	return 30 * time.Second
+}