Module improvements

[noise64]

Resolves GOL-57
Resolves GOL-393

This PR completes the same-process module-loader work.

What this enables

• loads installed node_modules with Node-style package entry points, exports/imports maps, conditions, self-references, extensions, directories, and symlinks.
• runs mixed CommonJS/ESM dependency graphs, including require(esm), CJS named exports/reexports, JSON import attributes, cycles, and Node-compatible cache behavior.
• preserves mutable Node module APIs such as require.cache, require.extensions, Module._pathCache, custom extension handlers, and side-effect-free require.resolve.
• supports same-process programmatic loader hooks and validates real npm package graphs across HTTP, database, cloud SDK, logging, validation, and data-format libraries.

Accepted follow-up boundaries are limited to:

• simulated Node CLI, preload, process.execPath, and spawned-process loader modes;
• TypeScript stripping/transpilation and Amaro;
• worker-thread-only behavior;
• native .node, WebAssembly/V8-specific behavior, and other true WASI/platform gaps;
• non-core VM realm/GC/leak behavior and Node-internals-only tests.

Ordinary same-process package resolution, module-kind detection, registered-loader behavior, and CommonJS/ESM interop are covered here and are not deferred.

Node compatibility

• CI-enforced passing entries: 3,085 → 3,234 (+149).
• primary covered surface (runnable + known-gap): 4,295 → 4,425 (+130); known gaps 1,210 → 1,191 (−19); passing coverage 71.8% → 73.1%.

Functional followups

• GOL-54 — complete non-core node:vm realm, GC, leak, and cached-data behavior.
• GOL-325 — propagate HTTP abort cancellation to the underlying WASI request.
• GOL-359 — synchronize live ESM exports for every loaded builtin.
• GOL-361 — normalize QuickJS property-redefinition errors.
• GOL-386 — fix pipelined HTTP keep-alive request sequencing.
• GOL-388 — canonicalize real host symlinks for module identity.
• GOL-389 — emit socket timeouts when pending writes stop progressing.
• GOL-390 — route CommonJS loading through public Module hooks.
• GOL-391 — preserve unrelated rejections during failing require(esm).
• GOL-392 — restore Node-compatible unhandledRejection turn ordering.

Performance / CI related followups

• GOL-347 — benchmark module-loader artifact size and startup.
• GOL-348 — cache negative package.json lookups.
• GOL-349 — cache repeated require(esm) graph analysis.
• GOL-350 — reduce cold module-resolution filesystem probes.
• GOL-351 — remove module-resolver hot-path micro-costs.
• GOL-352 — diagnose the concurrent string_decoder hang.
• GOL-360 — fix large TCP write backpressure stalls.
• GOL-387 — diagnose WASI HTTP incomplete-message flakes.