harness: adapt pinned Wasmtime component tests and async guests

[lannbot]

Summary

• Adapt the Cargo-locked Wasmtime component-model WAST corpus to the existing generator/executor, with recursive discovery, preserved provenance, reviewed configuration inventory, and isolated bounded workers.
• Supply the portable Wasmtime test-host functions/resources. Reject unrelated instantiation traps, stale/changed expected failures and skips, incomplete worker results, and infrastructure failures.
• Build upstream stackless round-trip and resource short-read guests from clean pinned sources; exercise the public API with concurrent calls, controlled host settlement, short reads, and resource transfers under FIFO and seeded scheduling.
• Wire supplementary Deno gates into core CI and just gates. Runtime implementation behavior is unchanged; residual coverage gaps are tracked in testing: triage classified Wasmtime supplementary coverage gaps #372 and deferred threads in memory64 + shared-everything threads: deferred feature tracking #12.

Coverage

88 WAST files / 850 commands accounted for:

• 515 passes: 334 setup commands and 181 assertions
• 157 exact classified failures
• 4 classified skips
• 174 excluded commands across 5 files (memory stress, component GC, fixed-feature configuration mismatch)
• zero unexpected results or infrastructure failures

Public guest tests: 3 passed under FIFO and 3 passed under seed 1. This is supplementary regression coverage, not an all-pass conformance claim.

Verification

• All recipes in just gates < /dev/null completed. Initial run stopped at missing Playwright executables; just browsers-install, then just browsers, just smoke-tls, and just smoke-c0 completed the remaining sequence. Consumer trees unchanged.
• Final focused reruns: testgen 6 tests, harness classifier/subprocess/runner 18 tests, supplementary WAST FIFO and seed 1, guest build/tests FIFO and seed 1.
• Guest componentization verified with CI's wasm-tools 1.247.0.
• Independent final review: LGTM.

Automerge will be armed with merge-commit policy after opening.