tsgo probe: functions without return type annotation resolve to unknown

[milkyskies]

When a .ts file has a function without an explicit return type annotation (relying on TS inference), the tsgo probe cannot resolve the return type and the Floe checker sees it as unknown.

Example:

// This works — explicit return type
export function useJiraIssues(...): UseQueryResult<IssueDto[], Error> { ... }

// This doesn't — inferred return type resolves to unknown in Floe
export function useJiraIssues(...) { return useQuery({ ... }); }

This causes cascading unknown types for destructured bindings (data, isLoading, error) and downstream type errors.

The tsgo probe generation needs to handle inferred return types, likely by probing the function's return value directly rather than relying on the declaration's type annotation.