feat(index): introduce Lumina vector index and enable Lucene builds

[zjw1111]

Purpose

Linked issue: N/A

This PR introduces the Lumina-backed vector global index and enables Lucene index builds.

• Add the Lumina global index implementation and unit tests under src/paimon/global_index/lumina.
• Download the prebuilt Lumina 0.2.3 package from Paimon C++ OSS storage and install its shared library.
• Fetch Boost from a configurable URL, a local package, or the Paimon C++ OSS fallback, and remove the temporary guard that disabled Lucene builds.
• Enable Lumina and Lucene in applicable CI builds.
• Document the Lumina and Lucene build options, library targets, and index capabilities.

Alibaba copyright headers in the migrated Lumina files were replaced with ASF headers. The source LICENSE and NOTICE files contain no Lumina-specific entries. The Boost source archive is downloaded at build time rather than bundled in the repository, so no legal-file update is needed. Contributor analysis found no threshold hits requiring Co-authored-by trailers.

Tests

API and Format

No public header or storage format changes.

Documentation

The build and global index documentation now covers Lumina and Lucene.

Generative AI tooling

Migrated-by: OpenAI Codex

[lxy-9602]

+1

[JingsongLi]

+1