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_test.go

@@ -1,6 +1,9 @@
 package greet
 
-import "testing"
+import (
+	"context"
+	"testing"
+)
 
 func TestService_Greet(t *testing.T) {
 	service := NewService()
@@ -16,7 +19,7 @@ func TestService_Greet(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			result := service.Greet(tt.name)
+			result := service.Greet(context.Background(), tt.name)
 			if result != tt.expected {
 				t.Errorf("Greet(%q) = %q, want %q", tt.name, result, tt.expected)
 			}