BasicTilemapTestSuite: Split the remaining multi-scenario facts

[YYDan]

Description

BasicTilemapTestSuite was never covered by the summer 2024 refactor campaign, but it is already close to the target format — 45 asserts across 24 tests, 1.9 per test, with most tests already one assert each.

Only three need attention:

Test	Kind	Asserts	Lines
tilemap_get_frame	async	3	74
tile_set_get_empty	fact	3	44
draw_tilemap	async	0 direct	70

tile_set_get_empty is a straightforward split. The two async draw tests should be reviewed rather than split reflexively — each drives multiple frames, and draw_tilemap performs its verification through the draw-comparison helpers rather than direct asserts, so it may need a different treatment entirely.

Separately, the suite's tests are not currently numbered; consider applying the <original_name> #N convention while in the file.

This is a small job and a good candidate for someone picking up the convention for the first time.

Script Name

BasicTilemapTestSuite

Steps To The Task

• Split tile_set_get_empty into one fact per scenario
• Review tilemap_get_frame and draw_tilemap and decide whether a split is worthwhile given they are multi-frame async tests, documenting the decision in the PR
• Apply the <original_name> #N naming convention to any fact that gains siblings
• Add section comment headers per family (tilemap_* vs tile_* vs draw tests)
• Update assert descriptions so they identify the specific scenario
• Run the suite on VM and YYC and confirm the same set of checks pass as before