build: fetch Lumina from release package

[zjw1111]

Purpose

Linked issue: N/A

Replace the vendored Lumina headers, shared library, and documentation under third_party/lumina with the official Lumina v0.3.0-rc1 release package.

This change:

• downloads the precompiled release archive through ThirdpartyToolchain.cmake, with environment and local-package overrides;
• verifies the archive using its SHA256 checksum and installs headers and liblumina.so from the release directory layout;
• exposes Lumina through an imported CMake target so its build dependency and include path are propagated explicitly;
• removes the vendored third_party/lumina directory; and
• updates documentation references to the release package layout.

Tests

• cmake -S . -B /tmp/paimon-lumina-oss-config -DCMAKE_BUILD_TYPE=Debug -DPAIMON_BUILD_TESTS=ON -DPAIMON_ENABLE_LUMINA=ON
• cmake --build /tmp/paimon-lumina-oss-config --target lumina_ep -j 64
• cmake --build build --target paimon-lumina-index-test -j 64
• ./build/debug/paimon-lumina-index-test --gtest_brief=1 (15 tests passed)
• pre-commit run --files <changed files>
• git diff --check

API and Format

No public API, storage format, or protocol changes.

Documentation

Updated Lumina option references to point to docs/reference in the release package.

Generative AI tooling

Generated-by: OpenAI Codex (GPT-5)

[lxy-9602]

+1

[lucasfang]

+1