docs: require ingest for new field records - #665

What changed

• Require Ingest for new Field records and recognise sufficiently documented chat notes as a valid input alongside source files.
• Check provenance and independent team access before Field publication. Treat an explicit request to add firsthand notes as sufficient approval when the submission passes the checks and preserves the evidence.
• Align the Ingest and onboarding instructions with the contract. The assistant stages chat text for the existing file-based CLI.

How it is verified

• git diff --check and the onboarding integrity test passed.
• The Windows notation checker reproduces the existing Knowledge Store fixture link failure. GitHub runs the notation and Ingest checks on Linux.

Checklist

• Based on main and limited to one concern.
• Commit signed off for DCO.
• No internal work-item references.