[Fix-4578][admin] Fix PostgreSQL job model overview

[gordan-zhang]

Purpose of the pull request

Fix the Home page batch/stream job overview returning zero counts when Dinky uses PostgreSQL as its metadata database.

Closes #4578.

Brief change log

• Count batch_model with explicit boolean predicates that work with PostgreSQL and remain compatible with MySQL/H2.
• Compare normalized lowercase dialect values so PostgreSQLPrepareInterceptor lowercasing the SQL does not break matches against stored values such as FlinkSql.
• Add an explicit result map with snake-case SQL aliases for stable PostgreSQL-to-Java property mapping.

Verify this pull request

• Parsed TaskMapper.xml successfully with an XML parser.
• Ran git diff --check successfully.
• Verified the mapper against Dinky 1.2.5 with PostgreSQL 18: the API changed from streamingJobCount: 0 to the expected streamingJobCount: 10, with batchJobCount: 0.
• Confirmed two existing Flink streaming jobs remained RUNNING after the Dinky-only restart.