Add fallback provider chain and automatic retries to Venice AI client

[devJaja]

Goal: Awareness-resistant inference.
Why it matters: A single provider outage halts all coordination.
Proposed scope:

• Configurable provider fallback list, per-call timeouts, retries with backoff, graceful degradation to cached results.
  Acceptance criteria:
• Provider failure triggers failover without failing the task.
• Circuit breaker opens after repeated failures.

[MarcusDavidG]

@MarcusDavidG has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I can handle this issue and will like to work on it, Please assign thank you.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @MarcusDavidG to this issue.

[drips-wave]

Congratulations, @MarcusDavidG! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @MarcusDavidG: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@MarcusDavidG's PR #468 was approved and merged by @devJaja.

🏆 @MarcusDavidG: You earned 40 FoxPoints for this contribution! Your current tier: Builder (1,708 total points). Track your full progress on GrantFox.

👏 Great work, @MarcusDavidG! Keep contributing to Epta-Node.