build: use xtc-build for host artifacts

[guillon]

Motivation

Replace hand-written compiler, archiver, and linker invocations with the reusable xtc-build package.

Description

Use xtc-build to compile and link C-source and archive HostModule evaluators.

Update the TVM packed operator wrapper to describe its objects, archives, shared libraries, and architecture-specific toolchain through xtc-build. Preserve additional source flags and existing output filenames.

Add the xtc-build~=0.1.0 dependency.

This PR depends on #133, which introduces the TVM external_at support and additional C-source handling used by these changes.

Commits

• tvm: output all csrcs in temp dir
• build: use xtc-build for host artifacts

Discussion

The archive evaluator forces resolution of the payload symbol with -u rather than loading every member with --whole-archive.

TODO:

• Merge tvm: support external microkernels #133 before this PR.

Testing

• pytest tests/pytest/unit -q — 53 passed
• TVM shared-library, C-source, and archive backend variants — 6 passed
• External TVM microkernel test — passed
• Ruff checks on changed code
• Mypy check for TVMCompiler.py

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/xtc/backends/tvm/TVMCompiler.py	80.95%	2 Missing and 2 partials ⚠️
src/xtc/targets/host/HostAREvaluator.py	76.92%	2 Missing and 1 partial ⚠️
src/xtc/targets/host/HostCEvaluator.py	92.85%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!