Clean up the remaining multi-scenario facts left behind by the 2024 refactor campaign

[YYDan]

Description

The summer 2024 refactor campaign (issues #92–#171) reworked 30 suites, but a number of facts were missed or left deliberately grouped. None of these are large jobs individually — this issue collects them so they can be cleared in one pass.

Facts still holding several scenarios:

Suite	Fact	Asserts
BasicVariableTestSuite	parameter_string_tests (unnumbered, 112 lines)	8
BasicBufferTestSuite	buffer_base64_decode_test	6
BasicBufferTestSuite	buffer_get_used_size	6
BasicDataStructuresStackTestSuite	ds_stack_read_write test #3	6
BasicDataStructuresStackTestSuite	ds_stack_read_write test #2	5
BasicDataStructuresGridTestSuite	ds_grid_sort_test #1	6
BasicFileTestSuite	file_test #5, file_text_test #2	5 each
BasicVariableTestSuite	variable_instance_set_get_test #8–#11	4 each
BasicDataStructuresMapTestSuite	ds_map_array_reference_keys_test, ds_map_struct_reference_keys_test	4 each
BasicDataStructuresPriorityTestSuite	ds_priority_copy_test #1	4
ResourceAudioGroupsTestSuite	three facts at 4 asserts	4 each
BasicBufferTestSuite	buffer_decompress_test	4

Facts still carrying unlifted inline //#N scenario markers:

• BasicFileTestSuite — file_bin_test #3 through #7 (5 facts)

Naming convention not applied (ratios are already 1:1, so this is cosmetic but worth doing while in the files):

• BasicBufferTestSuite — only 11 of 42 facts numbered
• BasicMatrixTestSuite — only 3 of 14
• BasicSurfaceTestSuite — only 8 of 20
• BasicIniTestSuite — only 15 of 18

Not in scope: builtin_constant_varnames_test #1 in BasicVariableTestSuite is 849 lines but is a data table driving a loop over 2 asserts. It is an addTheory() candidate, not a split candidate, and should get its own issue if we want to pursue it.

BasicMathTestSuite and BasicStringTestSuite are excluded — their remaining multi-assert facts are the deliberate shared-buffer and multi-return groupings agreed during #329.

This can be split into per-suite PRs if that is easier to review.

Script Name

Multiple — see description

Steps To The Task

• Split the listed multi-scenario facts, named <original_name> #N
• Lift the inline //#N markers in file_bin_test #3–#7 into their own facts, preserving the comments as inline descriptions
• Apply the <original_name> #N naming convention in BasicBufferTestSuite, BasicMatrixTestSuite, BasicSurfaceTestSuite and BasicIniTestSuite
• Confirm per-suite assert counts are unchanged and that no fact name is duplicated in any suite touched
• Run the affected suites on VM and YYC and confirm the same set of checks pass as before