[IC-092] Add failure-injection tests for Redis, database, storage, AI, and provider outages.

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Outcome

Add failure-injection tests for Redis, database, storage, AI, and provider outages.

Acceptance checks

• Recovery avoids data loss/double decisions; degraded states are observable; each failure maps to a runbook.

Dependencies

IC-027, IC-035, IC-087

Planning metadata

• Priority: P1
• Milestone: Milestone 9 — Operations and pilot readiness

Definition of done

• Automated tests cover the change where practical.
• Tenant/environment isolation and failure paths were reviewed.
• Logs and errors contain no secrets, PII, documents, or biometric data.
• Relevant API, architecture, operations, and user documentation is updated.
• The pull request links this issue and lists verification commands.
  Generated from docs/planning/implementation-backlog.md; edit the backlog and rerun the sync to change generated fields.