Make Compiler scripts and tests portable across checkouts

[Happymic]

What changed

• Replace the standalone assembler parser's developer-specific input file with an explicit asm_file command-line argument.
• Replace developer-specific Python and PYTHONPATH examples in 12 TileLang test docstrings with repository-relative module invocations.
• Keep the GPT-OSS reference test compatible with both the two-value router API in Transformers 4.57.x and the three-value API on current Transformers main.

Why

The checked-in entry point and test examples referenced individual developers' home directories. They could not be reused from another checkout. The GPT-OSS test also depended on one specific Transformers API shape even though both shapes are still encountered in supported development environments.

Scope

The parser change affects only its direct __main__ entry point; library callers of parse_asm_file are unchanged. The TileLang changes are documentation-only. The GPT-OSS change is confined to the Hugging Face cross-check in one test.

Validation

• PYTHONPATH=. python -m pytest -q aten/tests -m 'not slow': 60 passed, 1 deselected.
• PYTHONPATH=. python -m pytest -q assembler/tests: 4 passed.
• PYTHONPATH=. python -m pytest -q aten/tests/test_gpt_oss_moe_reference.py: 11 passed with Transformers 4.57.6.
• python assembler/parser.py --help: command-line interface renders correctly.
• git diff --check: passed.

The TileLang suite was not executed locally because this checkout's Python environment does not include TVM. The only changed lines in those files are the Run: docstrings; no TileLang test logic changed.