Add DataEntity subtype support for platform-level classification

[medhwu]

What

Re-introduces a lightweight subtype column on the data_entity table so that data entities of the same type can be classified by their underlying platform/engine/tool.

New enum DataEntitySubTypeDto covers 60+ subtypes across 8 entity types including StarRocks, Doris, TiDB, FineBI, DataEase, RocketMQ, Pulsar and more.

Subtype is auto-detected from collector metadata -- the ingestion mapper reads platform / engine / tool / service_type keys.

A new policy condition key dataEntity:subtype enables platform-specific RBAC rules.

Why

All relational DB tables (PostgreSQL, MySQL, StarRocks, Doris, TiDB, ...) are classified as a single TABLE type. Similarly, all BI dashboards are DASHBOARD. This makes it impossible to filter by engine or apply platform-specific governance policies.

How

1. Flyway V0_0_101: ALTER TABLE data_entity ADD COLUMN subtype VARCHAR(128) with partial index
2. DataEntitySubTypeDto: Java enum with 60+ values
3. IngestionMapperImpl.detectSubtype(): reads collector metadata, dispatches by type
4. IngestionServiceImpl.persistSubtypes(): batch-updates subtypes after creation/update
5. ReactiveDataEntityRepository.updateSubtypes(): raw DSL.field("subtype") to avoid JOOQ compile dep
6. Policy: dataEntity:subtype condition key in schema + resolver + comparer

Backward compatibility

• subtype is nullable -- all existing entities remain NULL
• Collectors without platform/engine metadata are unaffected
• No breaking API changes

Checklist

• Flyway migration uses IF NOT EXISTS and partial index
• EnrichedDataEntityIngestionDto constructor passes subtype to super
• Policy JSON schema extended with dataEntity:subtype condition key
• No JOOQ code-generation dependency at compile time