docs: add fault injection test plan

[GatewayJ]

Type of Change

• New Feature
• Bug Fix
• Documentation
• Performance Improvement
• Test/CI
• Refactor
• Other:

Related Issues

N/A

Summary of Changes

Adds a Chinese fault injection test plan for the RustFS Operator e2e harness.

The plan documents:

• how to reuse the existing destructive e2e entrypoint and Kind-based Tenant setup
• how to combine Chaos Mesh, an S3 workload, operation history, and a Jepsen-like checker
• initial P0/P1/P2/P3 fault scenarios for disk I/O errors, Pod failures, network partitions, silent corruption, and local PV corruption
• safety guardrails, checker invariants, artifact requirements, and phased rollout steps

Checklist

• I have read and followed the CONTRIBUTING.md guidelines
• Passed make pre-commit (fmt-check + clippy + test + console-lint + console-fmt-check)
• Added/updated necessary tests
• Documentation updated (if needed)
• CHANGELOG.md updated under [Unreleased] (if user-visible change)
• CI/CD passed (if applicable)

Impact

• Breaking change (CRD/API compatibility)
• Requires doc/config/deployment update
• Other impact:

Verification

git diff --check
make pre-commit

Additional Notes

No runtime code changes are included. This PR only adds the detailed e2e fault injection design document.

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