refactor(sqlengine): add extensible filter set rewriting

[egolearner]

Summary

• Centralize recursive filter normalization and introduce registries for group and set rewrite rules.
• Fix the incorrect rewrite of OR-connected not-equal predicates into NOT IN.
• Merge same-field equality/IN predicates under OR and inequality/NOT IN predicates under AND.
• Deduplicate exact literals in merged results using string_view keys while leaving standalone IN/NOT IN lists unchanged.
• Keep positive intersections under AND and semantic value canonicalization outside the initial rule set.
• Add regression tests for rewrite boundaries, invalid literals, duplicate handling, predicate ordering, and unsatisfiable-filter propagation.

Testing

• ninja -C build.release unittest.zvec_sqlengine
• clang-format -n --Werror on changed C++ files
• git diff --check