feat: filter organization dependencies by purl - #1610

Cursor (@cursor) review

PR Summary

Low Risk
Scoped CLI feature with validation and tests; no auth or data-path changes beyond optional API filter parameters.

Overview
Adds repeatable --purls filters to socket organization dependencies so org dependency inventory can be narrowed to specific packages (full PURLs, version optional). --offset help text is clarified to “number of dependencies to skip” instead of “page number”.

Filter values are parsed, trimmed, deduplicated, and validated before the API call (rejects bare names, empty flags, qualifiers, and subpaths). When filters are used, the CLI only shows results if the API’s purlFilters confirms every requested PURL; otherwise it fails with a clear error and no rows.

New docs/organization-dependencies.md (linked from the README) documents pagination and PURL filtering. Unit and CLI tests cover parsing, server confirmation, and invalid --purls usage.

^{Reviewed by Cursor Bugbot for commit cc8ba0a. Configure here.}