Description

The CLI should expose a lightweight top-level opencontext --version path that prints the installed package version and exits successfully.

Today, the CLI module eagerly pulls in the FastAPI/Uvicorn startup path, and it does not offer a dedicated top-level --version flag. That makes simple version inspection heavier than necessary and more brittle in environments that only need package metadata.

Expected behavior

• opencontext --version prints the package version and exits with status 0.
• The version path does not require importing FastAPI/Uvicorn or triggering application startup side effects.
• Existing integrations that reference opencontext.cli:app continue to work.

Why this matters

• Users and packaging/debugging tools expect --version to be cheap and reliable.
• Lightweight version inspection is useful even when web/runtime dependencies are unavailable.
• Preserving the legacy app entrypoint avoids breaking existing deploy or embedding workflows.