fix(fs): normalize local filesystem paths

[zjw1111]

Purpose

Linked issue: N/A

This PR fixes several filesystem and system-field handling issues:

• Use normalized local paths for LocalFileSystem::Rename, so file: URIs are not passed raw to ::rename.
• Normalize local file paths through LocalFile::Create, including empty paths as the current directory and relative paths as absolute paths based on the current working directory.
• Return LocalFile::Create, LocalFile::GetParentFile, and LocalFile::ListFiles results through std::unique_ptr<LocalFile> so callers use the validated factory and ownership is explicit.
• Move LocalFile ownership into LocalInputStream / LocalOutputStream, and make stream creation transfer ownership with std::unique_ptr<LocalFile>.
• Rename the normalized local path accessor from LocalFile::GetAbsolutePath to LocalFile::GetPath, and update local file tests to construct files through LocalFile::Create.
• Move working-directory lookup into PathUtil::GetWorkingDirectory and use dynamically allocated getcwd storage for deep working directories.
• Make ExternalPathProvider safe for concurrent path generation by replacing unsynchronized position_ mutation with an atomic round-robin counter.
• Treat rowkind as a special/system field in SpecialFields::IsSpecialFieldName, matching the already-defined SpecialFields::RowKind() field.

Tests

• git diff --check
• git diff --cached --check
• git diff --check origin/codex/fix-filesystem-issues..HEAD
• cmake --build build --target paimon-fs-test -j64
• ./build/release/paimon-fs-test
• ./build/release/paimon-fs-test --gtest_filter=LocalFileTest.*
• Earlier verification before the branch merged the latest main: cmake --build build --target paimon-common-test -j64
• Earlier verification before the branch merged the latest main: ./build/release/paimon-common-test --gtest_filter=ExternalPathProviderTest.*:PathUtilsTest.*
• Earlier verification before the branch merged the latest main: ./build/release/paimon-common-test --gtest_filter=SpecialFieldsTest.*
• Earlier verification before the branch merged the latest main: ./build/release/paimon-common-test --gtest_filter=ExternalPathProviderTest.*
• Latest cmake --build build --target paimon-common-test -j64 is currently blocked by an unrelated Parquet/Arrow API mismatch on the updated branch: WhenBufferedRanges / PreBufferRanges are not available on parquet::ParquetFileReader.

API and Format

No storage format or protocol changes. This adds an internal PathUtil::GetWorkingDirectory helper, renames an internal LocalFile path accessor to GetPath, and changes internal local-file ownership APIs to use std::unique_ptr<LocalFile>.

Documentation

No.

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Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

[lucasfang]

+1

[lxy-9602]

+1