feat(auth, docs): add SDK guides and local password support for management

- Added extensive SDK usage guides for `cliproxy`, `sdk/access`, and watcher integration.
- Introduced `--password` flag for specifying local management access passwords.
- Enhanced management API with local password checks to secure localhost requests.
- Updated documentation to reflect the new password functionality.

sdk/cliproxy/builder.go

@@ -142,6 +142,15 @@ func (b *Builder) WithServerOptions(opts ...api.ServerOption) *Builder {
 	return b
 }
 
+// WithLocalManagementPassword configures a password that is only accepted from localhost management requests.
+func (b *Builder) WithLocalManagementPassword(password string) *Builder {
+	if password == "" {
+		return b
+	}
+	b.serverOptions = append(b.serverOptions, api.WithLocalManagementPassword(password))
+	return b
+}
+
 // Build validates inputs, applies defaults, and returns a ready-to-run service.
 func (b *Builder) Build() (*Service, error) {
 	if b.cfg == nil {