verify-real: bootstrap cdxt on demand for the fetch step

Add content_languages filter; vendor index SQL to drop cdx_toolkit dependency

UI: drop Check-bucket button, align path field, gate Cancel on running job

Add make verify-real: real-path check against the live commoncrawl bucket

Read CC index via HF CDN (no bucket mount) + add Cancel Job button

Add CC WARC repackaging Space (Gradio + HF Jobs + cdx_toolkit)