flatbuffers: Add LoadBuffer utility

[paulquiring]

flatbuffers: Add LoadBuffer

score/flatbuffers/load_buffer.hpp — public API header with LoadBuffer functions returning a Result type
score/flatbuffers/details/load_buffer_internal.hpp — internal implementation details
score/flatbuffers/details/load_buffer.cpp — implementation translation unit
score/flatbuffers/details/load_buffer_test.cpp - unit test
score/flatbuffers/test/load_buffer_test.cpp - integration test

Build & CI changes

score/flatbuffers/BUILD - added flatbufferutils library for LoadBuffer
.github/workflows/coverage_report.yml — added --source-directory option
.gitignore — added cpp_coverage directory

Tooling fixes

.clang-tidy-minimal — renamed ExtraArgs → ExtraArgsBefore
.pre-commit-config.yaml — excluded load_buffer_internal.hpp from clang-tidy (private header with no compile commands; checked indirectly via load_buffer.cpp)
score/flatbuffers/examples/config_usecase/demo_app_test.cpp — minor cleanup

[github-actions]

The created documentation from the pull request is available at: docu-html

[OliverHeilwagen]

Only remaining point is API return type: Result vs expected.

[paulquiring]

Only remaining point is API return type: Result vs expected.

I just found out its score::os::Result (score::cpp::expected<R, score::os::Error>) vs score::Result. Surprisingly score::Result has it's how expected implementation. It looks like there is some history behind that. I'll add this to the baselibs meeting agenda.

[OliverHeilwagen]

Only remaining point is API return type: Result vs expected.

I just found out its score::os::Result (score::cpp::expected<R, score::os::Error>) vs score::Result. Surprisingly score::Result has it's how expected implementation. It looks like there is some history behind that. I'll add this to the baselibs meeting agenda.

In this case i would assume we should go with score::Result as it is more fitting for the other utility methods.
Discussion about the different expected implementation i would still appreciate. I think we analysed once and the Result version seemed more advanced, as it also supports the monadic operations in comparison to the futurecpp version.

[paulquiring]

@4og and @fbaeuerle would it be possible to squash merge this pr with the message:

flatbuffers: Add LoadBuffer

score/flatbuffers/load_buffer.hpp — public API header with LoadBuffer functions returning a Result type
score/flatbuffers/details/load_buffer_internal.hpp — internal implementation details
score/flatbuffers/details/load_buffer.cpp — implementation translation unit
score/flatbuffers/details/load_buffer_test.cpp - unit test
score/flatbuffers/test/load_buffer_test.cpp - integration test

Build & CI changes

score/flatbuffers/BUILD - flatbufferutils library for LoadBuffer
.github/workflows/coverage_report.yml — added external symlink creation for genhtml in coverage reporting (OSS flatbuffers headers)
.gitignore — added cpp_coverage directory

Tooling fixes

.clang-tidy-minimal — renamed ExtraArgs → ExtraArgsBefore
.pre-commit-config.yaml — excluded load_buffer_internal.hpp from clang-tidy (private header with no compile commands; checked indirectly via load_buffer.cpp)
score/flatbuffers/examples/config_usecase/demo_app_test.cpp — minor cleanup

[Copilot]

Pull request overview

Adds a new score::flatbuffers::LoadBuffer utility to load binary FlatBuffer files into either std::vector<uint8_t> or std::pmr::vector<uint8_t>, and wires it into examples, tests, Bazel, and CI tooling.

Changes:

• Introduce public LoadBuffer API plus internal OS-abstraction-based implementation and translation unit.
• Add unit + integration tests for success and error-path behaviors; update the config-usecase demo test to use the new API.
• Add Bazel targets and supporting CI/tooling tweaks (coverage symlink, clang-tidy config rename, pre-commit exclusions, gitignore).

Reviewed changes

Copilot reviewed 11 out of 13 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
score/flatbuffers/load_buffer.hpp	New public API header declaring LoadBuffer overloads and documenting error behavior.
score/flatbuffers/details/load_buffer_internal.hpp	New internal templated implementation using OS abstractions (open/fstat/read/close).
score/flatbuffers/details/load_buffer.cpp	Implements the public API by delegating to the internal implementation.
score/flatbuffers/details/load_buffer_test.cpp	Unit tests with OS mocks + smoke tests for public API.
score/flatbuffers/test/load_buffer_test.cpp	Integration tests performing real filesystem I/O and checking returned Error::Codes.
score/flatbuffers/examples/config_usecase/demo_app_test.cpp	Switch demo to use LoadBuffer instead of ad-hoc file reading.
score/flatbuffers/examples/config_usecase/BUILD	Add dependency on the new flatbufferutils library.
score/flatbuffers/details/idl_parser.cpp	Relocates/provides minimal FlatBuffers version symbol implementation.
score/flatbuffers/BUILD	Adds flatbufferutils library and new cc_test targets; updates flatbufferscpp source path.
.github/workflows/coverage_report.yml	Creates/removes an external symlink so genhtml can resolve external flatbuffers headers.
.gitignore	Ignores generated cpp_coverage output directory.
.clang-tidy-minimal	Renames clang-tidy config key to ExtraArgsBefore.
.pre-commit-config.yaml	Excludes load_buffer_internal.hpp from clang-tidy and updates exclude regex.

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[paulquiring]

Closes #126