runtime: implement WebAssembly/ESM integration for .wasm imports - #35587

`Bun__transpileVirtualModule` is a second entry into `transpile_source_code_inner` that can now return `tag == Wasm`, but its consumer — `handleVirtualModuleResult`'s `OnLoadResultTypeCode` branch (ModuleLoader.cpp:389-396) — still hands the result straight to `Zig::SourceProvider::create` without checking the tag. A `Bun.plugin` `b.module()` whose specifier ends in `.wasm` and omits `loader` now hits `SyntaxError: Invalid character '\\0'` on the `\0asm` header (previously it silently produced a

All 7 tests use `add.wasm`, which per this comment has *no import section* — so the defining behaviour of WebAssembly/ESM integration (a wasm module's `(import "mod" "name" ...)` entries becoming ES module dependencies routed through `moduleLoaderResolve`/`moduleLoaderFetch` with a `.wasm`-keyed referrer) is never exercised. The `moduleKey`/`SourceOrigin` wiring at ModuleLoader.cpp:1197-1200 exists precisely for that resolve→fetch→link chain; per REVIEW.md ("Cover the variant matrix" / "deleting

The `contains_char(specifier, b'?')` demotion runs after the loader is already determined, so it fires even when `Loader::Wasm` was set by an explicit `with { type: 'wasm' }` attribute rather than inferred from the `.wasm` extension. `await import('./module?v=1', { with: { type: 'wasm' } })` — where the type attribute is the *only* thing selecting the wasm loader — is silently demoted to the file loader and returns `{ default: '<path>' }`. The #16476 compat shim should apply only to extension-in

This test file belongs in `test/js/bun/wasm/` (which already exists and holds `wasi.test.js`), not `test/regression/issue/`. Per CLAUDE.md's Test Organization section, `test/regression/issue/` is reserved for true regressions — behavior that worked in a previous release and then broke — whereas #12434 is a feature request (WebAssembly/ESM integration was never implemented; the path-string return was a placeholder). Consider moving to `test/js/bun/wasm/esm-integration.test.ts`.