[BigDataDZ]

已被上游#76（main5385ed3）替代：当前主分支已经提供buildQueryAsync/buildQueryFromMetadata，并在executeQuery中等待异步元数据编译。本PR原先要修复的功能问题已不存在。剩余独有改动主要是查询构造器提取和附加回归测试，因此关闭以避免重复审阅；分支与提交保留。其余前置修复分别仍由#61–#69承载。

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原始说明：
Async business query execution loaded dataset/field metadata asynchronously, then called the synchronous buildQuery facade to load it again. A MySQL platform store exposes only async metadata APIs, causing execution to fail before reaching the business database. Extract the existing SQL compiler into buildDatasetQuery(dataset, fields, request, options). Preserve the synchronous public buildQuery facade; async execution now uses the metadata it has already loaded. SQL, binding order, disabled-field filtering, aggregation, limit probing, output semantics and audit behavior remain covered. businessDatasets shrinks from 1025 to 823 lines, below its 950-line baseline; the pure builder is 204 lines. Both async-only regressions failed before the fix. Real SQLite metadata and actual SQL execution cover aggregate results, truncation, disabled fields and failure logging. Existing query compiler/execution tests pass. Add an opt-in native MySQL platform plus business-datasource acceptance case using a real table, pool, query, metadata and logs, executed sequentially with existing persistence acceptance. Validation: focused 18/18; full suite 759 passed, 16 skipped, 0 failed; eval fixtures 14/14 (two judge results pending). Architecture errors reduced 30 to 29; no baseline increases. Includes validated prerequisites through #68. Independent review approved. Native MySQL CI passed all 4 persistence cases (0 skipped), including the new real business query; its second invocation against the same database also passed (1 passed, 0 skipped), confirming metadata cleanup. PostgreSQL/browser and both Docker configurations passed. The online unit step passed; its job remains red at existing architecture errors, so online eval is skipped. Combined with #69: 762 passed, 16 skipped, 0 failed; architecture errors reduced to 28. 本次邮件/审阅反馈核查后的更新：已合入当前main e19d784，解决上游合并#49–#54后产生的config/size-baseline.json冲突。冲突处理逐项取较低值，未提高任何已有基线；业务代码由Git自动合入。 当前head：62bf12d1138ee30ce06da36a2b0370b64eda171b。本地定向验证：ℹ tests 67; ℹ pass 64; ℹ fail 0; ℹ skipped 3。跳过项未计为通过。远端CI已重新触发，结果以最新Checks为准，规模门禁尚未宣称全绿。