[Improvement][DAO] Route upper-layer Mapper access through repository Dao consistently

[ruanwenjun]

Description

dolphinscheduler-dao/CLAUDE.md already documents the intent that
upper-layer modules should not call dao.mapper.* directly; they should
go through dao.repository.* (Dao), which wraps the Mapper. master /
worker / alert already have zero direct dao.mapper imports, so the
boundary is held in those modules.

However, the boundary is not held in dolphinscheduler-api, and is
partially leaking in dolphinscheduler-service and dolphinscheduler-tools.

Module	Files importing dao.mapper.*
dolphinscheduler-api	51
dolphinscheduler-service	3 (ProcessServiceImpl, CommandServiceImpl, CuringParamsServiceImpl)
dolphinscheduler-tools	2 (MigrateResourceService, MigrateLineageService)
dolphinscheduler-master	0
dolphinscheduler-worker	0
dolphinscheduler-alert	0

In addition, the following Mappers currently have no corresponding Dao
at all, so consumers have no choice but to depend on the Mapper:

AccessTokenMapper, AlertMapper, AlertGroupMapper,
AlertPluginInstanceMapper, AlertSendStatusMapper, AuditLogMapper,
ClusterMapper, DataSourceMapper, DataSourceUserMapper,
EnvironmentWorkerGroupRelationMapper, ErrorCommandMapper,
FavTaskMapper, K8sNamespaceMapper, K8sNamespaceUserMapper,
PluginDefineMapper, ProjectParameterMapper, ProjectPreferenceMapper,
ProjectUserMapper, QueueMapper, RelationSubWorkflowMapper,
WorkflowInstanceRelationMapper, WorkflowTaskRelationMapper.

Goal

Make the boundary hold uniformly:

1. Every Mapper used from the upper layers has a corresponding Dao in
   dao.repository.
2. Every upper-layer file (api / service / tools) replaces its
   dao.mapper.* import with the Dao.

Plan

One Mapper per PR, matching the cadence already used by the
ProjectMapper and WorkflowDefinitionMapper migrations:

1. Pick a Mapper referenced from api / service / tools.
2. Ensure the Dao exposes every method the upper layer needs (add
   missing methods; adapt signatures where the Dao chooses a richer
   return type such as Optional<T>).
3. Replace every direct Mapper reference, including the corresponding
   tests (migrate mocks from WorkflowDefinitionMapper to
   WorkflowDefinitionDao, wrap queryByCode stubs in Optional.of /
   Optional.empty, etc.).
4. Keep behavior 1:1 (e.g. Optional<T>.orElse(null) when the Mapper
   returned a bare nullable).

This issue is the umbrella; each Mapper migration is a separate PR
linking back here.

Progress

• ProjectMapper → ProjectDao
• WorkflowDefinitionMapper → WorkflowDefinitionDao (PR pending)
• Remaining Mappers per the lists above
• ProcessServiceImpl in dolphinscheduler-service and the
  tools direct Mapper users