c1aa2ebec5
Two HIGH issues surfaced by review of 3b8f00e:
1. ``_build_game_event`` was newly succeeding where the old store
raised ``ValueError("Invalid source type: game_event")``. The
coverage-assertion-symmetry comment was honest about it being
a path that didn't exist before, but silent broadening of the
create contract is a real behaviour delta — any internal caller
that previously caught the error would now succeed.
Make ``_build_game_event`` raise NotImplementedError. The
coverage assertion still passes (the entry exists), but the
historical "you can't create game_event sources through the
store" contract is preserved. game_event instances continue to
be wired up by the game-integration setup path.
2. The new ``create_source`` ran ``_check_name_unique`` BEFORE
``build_source``. When both ``source_type`` is invalid AND
``name`` collides with an existing source, the old code raised
``"Invalid source type: …"`` first; the new code raised the
name-collision error. Swap the order: build first (which
validates source_type), then check name uniqueness, then
persist. Bonus: a uuid is no longer minted for a source we end
up rejecting on type.
New test pins the game_event NotImplementedError so a future
refactor doesn't accidentally re-open the create path.
38 value-source-store + factory tests stay green; ruff clean.