feat: bearer header auth for remote ingest endpoint
Adds Bearer token authentication as primary auth method for /ingest,
keeping URL-embedded key as legacy fallback. Adds keyless /ingest route
for Bearer-only clients. Updates remote CLI output to show 'api key'
instead of embedding key in ingest URL.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>