Enhance server with context initialization and graceful shutdown

- Added context-aware server initialization in cmd/server/main.go
- Implemented graceful shutdown handling with SIGINT/SIGTERM signals
- Added 30-second shutdown timeout for active connections
- Updated Greet service to use context.Context as first parameter
- Enhanced Zerolog integration with Trace level logging
- Added context-aware logging in Greet function calls
- Fixed route structure to use /api/v1/greet/* prefix
- Updated all handlers and tests to use context
- Comprehensive AGENTS.md documentation with verified commands
- Added server context management architecture section
- Updated API endpoint documentation with working examples

Changes:
- cmd/server/main.go: Complete rewrite with context and graceful shutdown
- pkg/greet/greet.go: Added context parameter and trace logging
- pkg/greet/api_v1.go: Updated interface and handlers for context
- pkg/greet/greet_test.go: Updated tests to use context
- cmd/greet/main.go: Updated CLI to use context
- pkg/server/server.go: Trace level config and context logging
- AGENTS.md: Comprehensive documentation update
- go.mod/go.sum: Added Zerolog dependency

All tests passing, server working with graceful shutdown verified.

pkg/greet/greet.go

@@ -1,5 +1,10 @@
 package greet
 
+import (
+	"context"
+	"github.com/rs/zerolog/log"
+)
+
 type Service struct{}
 
 func NewService() *Service {
@@ -9,7 +14,9 @@ func NewService() *Service {
 // Greet returns a greeting message for the given name.
 // If name is empty, it defaults to "world".
 // Implements the Greeter interface.
-func (s *Service) Greet(name string) string {
+func (s *Service) Greet(ctx context.Context, name string) string {
+	log.Trace().Ctx(ctx).Str("name", name).Msg("Greet function called")
+	
 	if name == "" {
 		return "Hello world!"
 	}