fix: propagate the API run id to the tracker

[davidberenstein1957]

What

EmissionsTracker.run_id is now a property backed by a locally generated uuid that returns the API run id as soon as one exists, and the API run is created in start() rather than on the first emission.

Why

With OutputMethod.API enabled, the tracker read run_id from CodeCarbonAPIOutput at construction time, but that handler builds its ApiClient with create_run_automatically=False and only creates the run lazily in _ensure_api_run. Nothing ever wrote the resulting id back, so tracker.run_id stayed None and _prepare_emissions_data recorded the literal string "None" in every row.

Consequences for users: CSV data could not be joined with the API data, on_csv_write="update" matched on "None" and overwrote the previous run's row, and per-task / BOAMPS filenames all collided on ..._None.csv.

Creating the run in start() (instead of only fixing the property) makes sure a single run has a single id everywhere, including rows persisted before the first API call. Failures there are logged and fall back to the local uuid, so an unreachable API no longer prevents tracking.

Verified

tests/test_emissions_tracker.py::TestCarbonTracker::test_run_id_with_api_output_is_never_none asserts tracker.run_id is not None and that the run id written to emissions.csv matches the API run id. It fails on master and passes with this change.

uv run pytest tests/test_emissions_tracker.py tests/output_methods tests/test_tracking_inference.py tests/test_api_call.py -q passes locally.

Closes #1303

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.51%. Comparing base (065d0e6) to head (922ebd2).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1327      +/-   ##
==========================================
+ Coverage   91.39%   91.51%   +0.12%     
==========================================
  Files          49       49              
  Lines        5056     5069      +13     
==========================================
+ Hits         4621     4639      +18     
+ Misses        435      430       -5     

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