Port Brave Sync server to Rust

Use SQLite for persistence and generate Rust protobuf bindings at build time.

Add Docker image support for containerized deployment.

Co-Authored-By: codex <[email protected]>

schema/protobuf/sync_pb/managed_user_shared_setting_specifics.proto

@@ -0,0 +1,33 @@
+// Copyright 2013 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// Sync protocol datatype extension for managed user shared settings.
+
+// If you change or add any fields in this file, update proto_visitors.h and
+// potentially proto_enum_conversions.{h, cc}.
+
+syntax = "proto2";
+
+option go_package = "./sync_pb";
+
+option java_multiple_files = true;
+option java_package = "org.chromium.components.sync.protocol";
+
+option optimize_for = LITE_RUNTIME;
+
+package sync_pb;
+
+// Properties of managed user shared setting sync objects.
+message ManagedUserSharedSettingSpecifics {
+  // The MU ID for the managed user to whom the setting applies.
+  optional string mu_id = 1;
+  // The key of the setting.
+  optional string key = 2;
+  // The setting value. The setting is a JSON encoding of an arbitrary
+  // Javascript value.
+  optional string value = 3;
+  // This flag is set by the server to acknowledge that it has committed a
+  // change to a setting.
+  optional bool acknowledged = 4 [default = false];
+}