refactor(blob): refactor BlobFileContext to honor the actual schema when classifying BLOB fields

[lxy-9602]

Purpose

Linked issue: #283

Classify BLOB fields by intersecting the option-configured fields with the columns actually present in the given schema, so partial (projected) schemas no longer pull in absent fields. Also removes the unused Is*Field query helpers.

Tests

BlobFileContextTest.PartialSchemaIgnoresAbsentFields
BlobFileContextTest.PartialSchemaWithOnlyBlobFileField

API and Format

Documentation

Generative AI tooling

Generated-by: Claude-4.8-Opus

[Copilot]

Pull request overview

This PR refactors BlobFileContext::Create to classify BLOB fields based on the intersection of (a) option-configured field lists and (b) the BLOB columns actually present in the provided (possibly projected) Arrow schema, preventing absent columns from being incorrectly treated as inline/view/descriptor/external-storage fields. It also removes now-unused per-field query helpers and updates unit tests accordingly.

Changes:

• Filter descriptor/view/inline/external-storage field sets to only include BLOB fields present in the provided schema.
• Derive blob_file_fields from “schema BLOB fields minus inline fields” (schema-aware).
• Remove Is*Field query helpers and adjust/add tests for partial-schema behavior.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/paimon/core/operation/blob_file_context.h	Removes unused Is*Field helpers from the public API.
src/paimon/core/operation/blob_file_context.cpp	Makes field classification schema-aware by intersecting option lists with BLOB fields present in the given schema.
src/paimon/core/operation/blob_file_context_test.cpp	Updates tests to use set getters and adds coverage for projected/partial schema scenarios.

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