[Improve] Clarify connected Brain sources

[roomote-roomote]

​Opened on behalf of @mrubens. Follow up by mentioning @roomote-roomote or in the web UI.

What changed

• Removed the Brain source-count summary tile and the connected-source ratio from the sources section.
• Limited the sources list to connected integrations.
• Renamed the steady-state source status from "Ingesting" to "Connected" while retaining "Backfilling" for bounded history replays and "Waiting" for connected sources that have not collected anything yet.

Why this change was made

The count and disconnected rows added noise to a page intended to explain what the Brain currently learns from. "Ingesting" also implied a transient operation even though it represented the normal active collector state.

Impact

Admins now see a focused list of active Brain sources with status labels that distinguish normal connectivity from meaningful replay or pre-collection states. Web lint, typecheck, focused tests, and pre-push checks pass. Browser proof could not be captured because the local app redirected Brain settings to mandatory inference setup.

[roomote-community]

No code issues found. See task

_{Reviewed c2f1ddb}