OpenAPI3 version value escapes `emitterOutputDir` and overwrites YAML/JSON outside the output tree
### Summary The `@typespec/openapi3` emitter retains the value of a `@versioned` enum member and interpolates it into the output filename as `{version}` without sanitizing path separators or traversal components. The completed path reaches the compiler's `emitFile()`, which creates the parent directory and writes the file without verifying containment under `emitterOutputDir`. A crafted declarative `.tsp` input can therefore create or overwrite an OpenAPI-formatted `.yaml` or `.json` file outside the configured output tree, subject to the compiler process's filesystem permissions. No executable TypeSpec extension or attacker-controlled Java
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