Parser changes are not exercised against minified JavaScript

Summary

Add a small minified/bundled-JavaScript fixture to the fast test suite so parser changes are exercised against the shapes minifiers produce.

Why

In #1126 a type-annotation validator raised from inside the arrow-return-type probe, turning the ordinary ternary c ? (a, b) : d << 2 into a SyntaxError. All 12,178 first-party tests and every differential suite passed. The regression surfaced only in the Web Tooling benchmark lane late in CI (prettier workload, bundle line 77573).

The blind spot: tests/ and scripts/differential/ contain no minified or bundled JavaScript, so the local gate never sees chained ternaries with parenthesised sequence expressions, shift operators in alternate branches, or single-line multi-megabyte functions. Those shapes are rare in hand-written source and ubiquitous in bundles.

Running a Web Tooling workload as a pre-flight is not realistic — it needs an upstream checkout plus npm install (docs/benchmarks.md:554).

Current behavior

./build/GocciaTestRunner tests in both modes, the differential harness, and every scripts/test-cli-*.ts harness pass without parsing a single minified file. A parser regression affecting only bundled code reaches CI.

Expected behavior

A checked-in minified fixture is parsed by the fast gate, so this class of regression fails locally.

Scope notes

• The #1126 fix landed in abe3be77; the guard in scripts/test-cli-parser.ts:1064 covers only the reduced ternary shapes, not the general class.
• Non-goal: replacing or duplicating the Web Tooling lane, which stays the real-world viability probe.
• Open questions for the implementer: whether the fixture is generated or vendored (and pinned how), whether it belongs under fixtures/ alongside ffi/ and modules/ or in tests/, and whether parsing alone suffices or it should execute.

Start with scripts/test-cli-parser.ts:1064 and run ./build/GocciaTestRunner tests in both modes to understand the fast gate. Add a checked-in minified or bundled JavaScript fixture to the fast-suite path, then verify it is parsed locally and covers the described bundled syntax shapes without replacing the Web Tooling lane.