refactor: split monolithic main.go into modular structure

Refactored 800+ line main.go into clean, domain-separated files:
- main.go (96 lines) - Entry point and command router only
- types.go - Type definitions and data structures
- client.go - HTTP client and request handling
- cmd_kv.go - Key-value operations (get/put/delete)
- cmd_meta.go - Resource metadata commands
- cmd_user.go - User management commands
- cmd_profile.go - Profile management
- cmd_cluster.go - Cluster operations (members/health)
- cmd_system.go - System commands (connect/auth/help)
- utils.go - Shared utilities (parsing, colors, completion)

No functional changes, pure reorganization for maintainability.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

cmd_system.go

@@ -0,0 +1,59 @@
+package main
+
+import "fmt"
+
+func (c *KVSClient) handleConnect(args []string) {
+	if len(args) < 1 {
+		fmt.Println(red("Usage: connect <base-url>"))
+		return
+	}
+	c.baseURL = args[0]
+	fmt.Println(green("Connected to:"), c.baseURL)
+}
+
+func (c *KVSClient) handleAuth(args []string) {
+	if len(args) < 1 {
+		fmt.Println(red("Usage: auth <token>"))
+		return
+	}
+	c.currentToken = args[0]
+	fmt.Println(green("Authentication token set"))
+}
+
+func (c *KVSClient) handleHelp(args []string) {
+	help := `
+KVS Interactive Shell - Available Commands:
+
+Connection & Authentication:
+  connect <url>              - Connect to KVS server
+  auth <token>               - Set authentication token
+  profile add <name> <token> <user-uuid> [url] - Add user profile
+  profile use <name>         - Switch to user profile
+  profile remove <name>      - Remove user profile
+  profile                    - List all profiles
+
+Key-Value Operations:
+  get <key>                  - Retrieve value for key
+  put <key> <json>           - Store JSON value at key
+  delete <key>               - Delete key
+
+Resource Metadata:
+  meta get <key>             - Get metadata (owner, group) for a key
+  meta set <key> [flags]     - Set metadata for a key
+    Flags: --owner <uuid>, --group <uuid>, --permissions <number>
+
+Cluster Management:
+  members                    - List cluster members
+  health                     - Check service health
+
+User Management:
+  user get <uuid>            - Get user details
+  user create <nickname>     - Create new user (admin only)
+
+System:
+  help                       - Show this help
+  exit, quit                 - Exit shell
+  clear                      - Clear screen
+`
+	fmt.Println(help)
+}