[WIP] Fix getTypeOfSymbol returning undefined for host-bound symbols

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

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This section details on the original issue you should resolve

<issue_title>getTypeOfSymbol returns undefined for host-bound symbols</issue_title>
<issue_description>makeRpcFacade short-circuits to undefined when resolveRpcSymbol cannot map a host-bound (volar virtual-doc) symbol, and the getTypeOfSymbol adapter (patches/typescript/overlay/src/compiler/tsgoChecker.ts) returns that directly and memoizes it in typeOfSymbolCache.

Stock's getTypeOfSymbol never returns undefined — Variable/Property/Function/Class/Enum symbols get a computed type, everything else falls back to errorType (typescript/src/compiler/checker.ts:12960).

Same category as the getDeclaredTypeOfSymbol fix in 5d548ad, but the fallback is not errorType here: returning errorType for a value/function symbol would be a silent wrong result. Needs a decision on the correct fallback for host-only symbols before fixing.
</issue_description>

• Closes getTypeOfSymbol returns undefined for host-bound symbols #64

Comments on the Issue (you are @copilot in this section)

• Fixes getTypeOfSymbol returns undefined for host-bound symbols #64