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>

types.go

@@ -0,0 +1,42 @@
+package main
+
+import "encoding/json"
+
+// Types matching the backend API
+
+type StoredValue struct {
+	UUID      string          `json:"uuid"`
+	Timestamp int64           `json:"timestamp"`
+	Data      json.RawMessage `json:"data"`
+}
+
+type Member struct {
+	ID              string `json:"id"`
+	Address         string `json:"address"`
+	LastSeen        int64  `json:"last_seen"`
+	JoinedTimestamp int64  `json:"joined_timestamp"`
+}
+
+type User struct {
+	UUID         string   `json:"uuid"`
+	NicknameHash string   `json:"nickname_hash"`
+	Groups       []string `json:"groups"`
+	CreatedAt    int64    `json:"created_at"`
+	UpdatedAt    int64    `json:"updated_at"`
+}
+
+type Group struct {
+	UUID      string   `json:"uuid"`
+	NameHash  string   `json:"name_hash"`
+	Members   []string `json:"members"`
+	CreatedAt int64    `json:"created_at"`
+	UpdatedAt int64    `json:"updated_at"`
+}
+
+// Profile represents a saved user configuration
+type Profile struct {
+	Name     string `json:"name"`
+	Token    string `json:"token"`
+	UserUUID string `json:"user_uuid"`
+	BaseURL  string `json:"base_url"`
+}