refactor(artifacts): harmonize Windows to Linux raw-file collection

Windows produced an intermediate C:\CI\output\artifacts.zip that
upload-artifact then re-zipped (zip-in-zip), while Linux deposited raw
files. Make both paths consistent: the build stages raw outputs into a
collect dir; collect zips it only as a transport archive, fetches, and
extracts into the host artifact dir; actions/upload-artifact produces
the single final archive.

- _windows_build: param artifact_zip -> output_dir; stage raw files
  (in-place when source IS the collect dir, else wipe+copy), no
  Compress-Archive; absolute artifact-source resolved.
- _windows_collect: zip guest dir as transport, fetch, extract (mirror
  _linux_collect); guest_path is now the collect directory.
- job.py / build_run CLI: pass output_dir; rename --guest-artifact-zip
  -> --guest-output-dir.
- Tests updated for the raw-file contract.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ci_orchestrator/commands/job.py

@@ -492,7 +492,7 @@ def job(
                 ip_address=ip_address,
                 credential_target=target,
                 workdir="C:\\CI\\build",
-                artifact_zip="C:\\CI\\output\\artifacts.zip",
+                output_dir="C:\\CI\\output",
                 host_source_dir=None,
                 clone_url=authed_repo_url,
                 clone_branch=branch,
@@ -526,7 +526,7 @@ def job(
                 _windows_collect(
                     ip_address=ip_address,
                     credential_target=target,
-                    guest_path="C:\\CI\\output\\artifacts.zip",
+                    guest_path="C:\\CI\\output",
                     host_dir=job_artifact_dir,
                     include_logs=True,
                 )