[wasm] Package CoreCLR native symbol map

[lewing]

CoreCLR browser builds already generate Emscripten's dotnet.native.js.symbols, but the browser runtime .nupkg did not contain it. This adds the existing file to the CoreCLR runtime-pack harvest, matching Mono, so WasmEmitSymbolMap=true can publish native symbols without forcing an application relink.

The Emscripten index:name payload remains unchanged. The boot resource model now retains the symbols file's SHA-256 alongside the existing final-wasm SHA-256, so fingerprinted published files can be discovered and verified as an exact pair.

Validation includes an independent WebAssembly import/function/code/export parser and Emscripten-map parser. It verifies absolute module function indices include imports, checks runtime/interpreter/libc/exported/compiler-generated anchors, and rejects shifted indices, stale wasm identity, and mutated symbol-map bytes.

Current Release artifacts:

Artifact	Size	SHA-256
dotnet.native.wasm	4,698,251 bytes	4abe2a6ca7e5cc5f8bc674d0a111e7e3e3ed1f78cc2c28a0387d74b8ce22fd04
dotnet.native.js.symbols	655,281 bytes	19b6b201a88b019db6b822a2baf3e5a8022f54ef4e385633b931255e80b1ef4b

The runtime .nupkg grew from 71,838,978 to 71,984,589 bytes (+145,611 bytes, 0.20%). Application publish remains opt-in through WasmEmitSymbolMap.

Live Chrome/CDP cross-check:

• V8 stopped at absolute function index 9614, resolved by the map as BrowserHost_ExecuteAssembly.
• V8 then stopped at stripped $func2243; the map resolves index 2243 to InterpExecMethod(InterpreterFrame*, InterpMethodContextFrame*, InterpThreadContext*, ExceptionClauseArgs*).
• Its stripped caller $func2276 resolves to ExecuteInterpretedMethod.

R2R transition thunks are functions in separately loaded Webcil modules and remain covered by their module-local name sections from #132906; they are intentionally not folded into this native-host map.

Validation run:

• PATH=/opt/homebrew/bin:$PATH ./build.sh -os browser -c Release -subset clr+libs
• Wasm.Build.Tests.ModuleConfigTests.RuntimePackSymbolMapMatchesFinalWasm — 1 passed
• Wasm.Build.Tests.ModuleConfigTests.RuntimePackSymbolMapRejectsIndexAndIdentityMismatches — 1 passed
• Wasm.Build.Tests.ModuleConfigTests.SymbolMapFileEmitted — build and publish cases passed, including fingerprinted static assets
• Wasm.Build.Tests.ModuleConfigTests.SymbolMapFileNotEmitted — build and publish opt-out cases passed

Resolves #134009

Note

This pull request was generated by GitHub Copilot.

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