[JingsongLi]

Purpose

Paired PyPaimon integration: apache/paimon#10724.

Allow PyPaimon to assemble ordinary search source plans and use Ray for placement while Rust Core owns query execution and global coordination.

Changes

• Make VectorScanPlan and FullTextScanPlan snapshot-and-split data with public constructors, synchronous source access and validated serde restoration. Plans carry no live table, SDK handle, query configuration or fingerprint.
• Execute explicitly supplied sources without discovering additional indexes or uncovered raw ranges. Readers own the schema, query, options, filters, authorization and FileIO, and resolve data-file/deletion-vector metadata at the captured snapshot.
• Preserve global ANN candidate selection before refinement, one raw BM25 corpus and hybrid rank fusion. Keep task batching bounded and share repeated immutable inputs between workers.
• Keep shard task transport out of the default public Core API. Repository bindings use a hidden internal-api bridge; the Python SDK exposes public Plan constructors and Read methods, with private scheduler callbacks.
• Support transported plans, reader-added filters, captured empty plans, primary-key source payloads and schema-only field renames. Capture full snapshots for decoded Java bucket splits without changing the C ABI.
• Derive indexed partition masks from pinned data-file row ranges. Keep full predicates on raw sources and intersect partition, scalar and caller masks before ANN Top-K.

Validation

• Rust 1.98.0 Core vector tests: 79 passed; full-text tests: 40 passed; hybrid tests: 22 passed.
• Primary-key vector unit tests: 31 passed; Java bucket-split integration tests: 7 passed.
• Python binding constructor/metadata codec tests: 3 passed; scheduler callback tests: 3 passed. These exercise real Python binding classes, malformed source payloads, concurrency, original cancellation errors and generator cleanup.
• C bridge reading the Java bucket-split fixture: 1 passed.
• Strict Clippy for default Core, full-text Core test targets and Python binding production/test targets passed with Rust 1.98.0 and -D warnings; formatting passed.

The Native extension is not rebuilt or installed into the PyPaimon test environment. There is no storage-format change or distributed primary-key search extension.