fix: sync missing changes after repository migration

[zjw1111]

Purpose

Linked issue: N/A

This PR synchronizes the remaining fixes and follow-up changes from the Alibaba Paimon C++ repository after the Apache migration.

• Make the installed CMake package configuration relocatable (alibaba/paimon-cpp#306).
• Fix thread safety in the file store path factory and union global index reader (#323, #395).
• Support null values when building Lumina vector indexes (#310).
• Add the field-name and index-type global index reader API (#391).
• Add executor coverage and fix global index writer cleanup after failures (#396, #398).
• Complete the remaining undefined-shift fixes from #308.
• Complete #333 by rejecting FLOAT and DOUBLE partition fields and removing their obsolete mapping and statistics paths.
• Remove Lance-specific build, source, and test references because Lance is not part of the Apache repository.
• Remove the unused path-based ReaderBuilder::Build overload left behind after the Lance cleanup.

The original authorship is preserved on the migrated commits. The branch was rebased onto the current Apache main, and the unrelated LICENSE/NOTICE cleanup from #153 is not included.

Tests

• Built all 1006 targets with static/shared libraries, tests, C++11 ABI, Avro, ORC, Jindo, Lumina, and Lucene enabled.
• Ran all 25 CTest targets; two IO fault-injection targets affected by parallel execution passed when rerun sequentially.
• Reran the six ReaderBuilder-related Common, Core, Blob, ORC, Parquet, and Avro test targets: 6/6 passed.

API and Format

Adds the global index CreateReader overload accepting field name and index type. Removes the unused path-based ReaderBuilder::Build overload. FLOAT and DOUBLE partition fields are now rejected. There are no storage format or protocol changes.

Documentation

Updates the build system documentation for relocatable package configuration. No new user-facing feature documentation is required.

Generative AI tooling

Migrated-by: OpenAI Codex

[lxy-9602]

+1