remove `DEALBOT_DISABLE_CHAIN` config env var

[silent-cipher]

DEALBOT_DISABLE_CHAIN allows running Dealbot without chain integration. However, chain interaction is a core dependency for Dealbot’s functionality, and disabling it results in running none of the checks agains sp.

This flag does not appear to provide meaningful value and may introduce confusion or unintended usage.

Notes -

• A broader refactor of app.config.ts is being considered separately (see a single dealbot should be able to talk to both mainnet & calibration #297)

[silent-cipher]

From what I can tell, this was mainly used to start the API without chain integration. With metrics APIs going away in PR #436, this might not be needed anymore.

Let me know if I’m missing any other intended use here.

[SgtPooki]

I agree, we should remove this

[BigLep]

Triage comment from 2026 FOC Board Triage (Post GA): easy to do, no significant change to anything significant when done...