fix: avoid forced exit after embedding analyze

[aro-has00]

Summary

• let successful embedding-enabled analyze runs unwind naturally instead of forcing process.exit(0)
• keep the existing forced-exit behavior for successful non-embedding analyzes
• add unit coverage for embedding analyze shutdown classification

Why

On macOS arm64 / Node 20, local embedding runs initialize transformers.js / ONNX Runtime successfully, write metadata and embeddings, then abort during process.exit(0) with:

libc++abi: terminating due to uncaught exception of type std::__1::system_error: mutex lock failed: Invalid argument

A minimal probe showed natural Node exit after local embedding is clean, while process.exit(0) after embedder initialization reproduces the abort. This matches the post-success crash reported in #151.

Validation

• npm test -- analyze-embeddings-limit.test.ts
• npx tsc --noEmit
• patched source CLI on disposable repo with --embeddings --skip-agents-md: EXIT_CODE=0, EMBEDDINGS=1
• patched source CLI on disposable repo without --embeddings: EXIT_CODE=0

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