fix(ci): perf tests — use `python -m pytest` so `src` import resolves (#914)

The Performance Tests job collected 26 items then aborted with
`ModuleNotFoundError: No module named 'src'` on test_frame_budget.py,
which does `from src.core.csi_processor import CSIProcessor`. The bare
`pytest` console script does not put the cwd (archive/v1) on sys.path;
`python -m pytest` does. pytest aborts the whole session on a collection
error, so this one import masked the entire (otherwise mock-based,
self-contained) perf suite.

Verified locally: bare-script path reproduces the exact error; `-m`
resolves it and test_frame_budget.py passes 3/3. The other two files
(test_api_throughput.py mock server, test_inference_speed.py MockPoseModel
+psutil) are fully self-contained — no test hits the running server.

Closes the last red job in the v1-API CI chain (#910/#911/#913).

.github/workflows/ci.yml

@@ -288,7 +288,11 @@ jobs:
         # command always failed with "Could not find ...". Run the real suite.
         # -o addopts="" drops the root pyproject's --cov/--cov-fail-under=100
         # flags (pytest-cov isn't installed here and 100% cov is for unit tests).
-        pytest tests/performance/ -o addopts="" -v --junitxml=perf-junit.xml
+        # `python -m pytest` (not the bare `pytest` script) puts the cwd
+        # (archive/v1) on sys.path so test_frame_budget.py's `from src.core...`
+        # import resolves — the bare script omits cwd and raises
+        # ModuleNotFoundError: No module named 'src'.
+        python -m pytest tests/performance/ -o addopts="" -v --junitxml=perf-junit.xml
 
     - name: Upload performance results
       if: always()