JIT: keep tslang's cache on (pre-alpha94 fixed the multi-module crash)

[ASDAlexander77]

Summary

tslang pre-alpha93's JIT cache crashed any run that compiled two or more modules (TypeScriptCompiler#548). Every example imports core/input_pass.ts and, through it, core/donut.ts, so run_jit.bat passed --jit-cache=false.

pre-alpha94 fixes the crash (TypeScriptCompiler#549), so this removes the workaround. The README now explains where the cache lives (__jit next to each source, ignored by git) and when a module is compiled again: when it, a file it imports, its options or tslang change. The cache manifest rejects objects that another tslang compiled.

Verification with pre-alpha94

• AOT build: all .ts objects deleted and rebuilt: 598/598 steps, no warnings. CTest: 57/57 pass.

• JIT: cache on, starting from an empty cache, two runs per example. All passed both times. The second run loads from the cache:

  Example	First run	Cached run
  meshlet_render -dx12 -test	1.6 s	0.4 s
  denoised_rtao -dx12 -test	4.5 s	3.3 s
  memory_management -dx12 -test	2.1 s	1.2 s
  host_image_copy -vk -test	1.3 s	0.5 s
  headless -dx12	Test PASSED	Test PASSED

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