TAPP as interpreter backend

[evaleev]

No description provided.

[Copilot]

Pull request overview

This PR introduces a new TAPP-based evaluation backend for SeQuant, wiring it into the build system and adding both unit and integration coverage to validate correctness against manual contractions/permutations and SCF integration behavior.

Changes:

• Add a header-only TAPP backend (TAPPTensor, ops, Result integration, EvalExpr integration) and MBPT biorthogonal cleanup support for TAPP tensors.
• Add unit + integration tests for the TAPP backend, and hook them into the test CMake targets conditionally on SEQUANT_HAS_TAPP.
• Extend CMake packaging/build to find or fetch the tapp-reference dependency; update external dependency pins; fix a BTAS unit test assertion.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tests/unit/test_eval_tapp.cpp	New unit tests validating TAPP evaluation, symm/antisymm, and biorthogonal cleanup behaviors.
tests/unit/test_eval_btas.cpp	Fixes an incorrect assertion and strengthens the comparison between two evaluation paths.
tests/unit/CMakeLists.txt	Adds conditional compilation/linkage of the new TAPP unit test object library.
tests/integration/eval/tapp/data_world_tapp.hpp	Provides TAPP-backed data world for integration SCF tests (mirrors BTAS version).
tests/integration/eval/tapp/scf_tapp.hpp	Implements SCF driver using TAPP backend evaluation (mirrors BTAS version).
tests/integration/eval/tapp/main.cpp	Integration test entry point for TAPP SCF run and energy check.
tests/integration/eval/CMakeLists.txt	Adds conditional eval_tapp integration executable and ctest entry.
SeQuant/core/eval/backends/tapp/tensor.hpp	Introduces TAPPTensor container bridging to the TAPP C API tensor-info handle.
SeQuant/core/eval/backends/tapp/ops.hpp	Implements TAPP-based contract/permute/scal/dot ops used by the Result backend and tests.
SeQuant/core/eval/backends/tapp/eval_expr.hpp	Adds TAPP-specific EvalExpr with TAPP-compatible annotation.
SeQuant/core/eval/backends/tapp/result.hpp	Implements ResultTensorTAPP integration (sum/prod/permute/symm/antisymm).
SeQuant/domain/mbpt/biorthogonalization.hpp	Adds TAPP overload for biorthogonal_nns_project.
cmake/modules/FindOrFetchTAPP.cmake	New module to find or FetchContent the TAPP reference implementation and patch/install targets.
cmake/modules/FindOrFetchBTAS.cmake	Fixes BTAS tag variable name used for FetchContent.
cmake/sequant-config.cmake.in	Extends installed package config to locate tapp-reference when not built from source.
external/versions.cmake	Updates pinned dependency tags and adds BTAS/TAPP tracked tags.
CMakeLists.txt	Adds SEQUANT_TAPP option, builds SeQuant::eval::tapp target, and wires export/module lists.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.