* refactor(constants): single source of truth for data dir + merge core/src constants
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* docs(contributing): use named src.constants for data paths, drop core/constants references
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* feat: support for embedding API key
* feat: encrypt and decrypt embedding API key
* test: add unit tests for EmbeddingClient authorization header behavior