refactor(parser): migrate to unified function API

[zhen8838]

Why

• Replace the legacy parser with the unified Pattern/Rule parser without compatibility readers, retarget metadata, or hidden dtype promotion.

What

• Defer in-module function parsing until child Modules are available, then resolve declarations in source order.
• Keep explicit scalar casts on the ordinary CallPattern -> ConstantPattern -> Cast Call path.
• Treat UMAT-only Call results as scalar expressions rather than GMEM placement values.
• Move retained legacy parser coverage under tests/parser and update the parser spec.

Contract

• parse_function(fn, context) remains the only parser entry point.
• Binary dtype matching stays strict; authored mismatches use explicit casts.
• Parser Rules do not inspect concrete Cast(Constant) combinations.

Risk

• Source full verification: 887 passed, 4 skipped.
• Installed full verification: 175 passed, 0 skipped.
• JUnit, coverage, commands, and outputs are retained under test_results/parser-scalar-call-*-full-r1/.

[zhen8838]

Why is this code? In this way, it will be executed when it becomes import.

[zhen8838]

Isn’t this paragraph the compatible code used for development? Why don‘t you delete it?

[zhen8838]

Why is Parser Sugar imported from there? Shouldn’t it be a part of Parser? Then I don‘t think the position of this test is reasonable.

[zhen8838]

CI run 32637567894 completed. Pre-commit passed; the test job reproduced the same five baseline failures as the clean-main verification (879 passed, 5 failed, 4 skipped), with no new M11-specific failures. The run stopped before wheel/install checks because the repository CI treats baseline failures as job failure.

Local fresh evidence for commit 86de9ce: test_results/parser-migration-m11-20260823e/ (JUnit junit.xml, coverage XML, command/output artifacts). M11-focused blast-radius tests passed: 27 passed.

[zhen8838]

Follow-up CI run 32638014364 on docs commit 52e6023 also completed: pre-commit passed and the test job reproduced the same five baseline failures (no new parser/M11 failure). The wheel/install stages were skipped by the workflow after the repository test job failed. PR remains open for human review; no merge was performed.