Adds documents-ingest-paperless: paginated GET /api/documents/, maps each
doc to a source='paperless' envelope per plan §4.2-4.3, reusing
kb_mail.Envelope/insert_envelope unchanged (packages/kb-mail not touched).
Cross-source link (source_mail entity) is a deterministic join of
original_file_name against the phase-1 registry.json consume_name index —
no heuristics, no correspondent guessing (plan decision 4). Stats always
balance (fetched = already_in_db + inserted + errors) and main() now also
exits non-zero on imbalance, not just on errors>0, matching the exit-code
convention already established in gmail-bulk-import.
Verified live on PIHA (rsync to /tmp, ~/kb/venv, PIHA checkout untouched):
dry-run then --apply inserted 186/186 paperless envelopes (0 errors,
180 source_mail links), a second --apply reported inserted=0/already_in_db=186
(idempotent), gmail rows stayed at 225030 and document_chunk stayed empty.
Rotated the kb-ingest Paperless API token after it was accidentally
partially echoed during recon (old token now dead).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
