perf(benchmarks): Add AWS sustained baseline

[rahulbsw]

Summary

• add a cost-bounded Terraform and ECS-on-EC2 benchmark environment with no public ingress or public IPs
• correct container startup dependencies and preserve the Confluent Python runtime
• publish a schema-v3 sustained AWS baseline: 106,692.65 msg/s median across three 120-second engine-saturated repetitions
• consolidate benchmark documentation and add the validated headline to GitHub Pages

Validation

• exact 16,200,000 ingress, consumed, produced, delivered, and independently observed output records per repetition
• zero processing or delivery errors; 0.0580% coefficient of variation
• benchmark helper tests: 8 passed
• Rust suite: 474 passed, 0 failed, 30 ignored
• Terraform fmt and validate passed before provisioning
• ECR scan completed with zero critical findings
• Terraform destroyed 45 resources; direct inventories show zero live benchmark resources

Security and cost

• private subnet only; no IGW, NAT, load balancer, SSH, public IP, or public CIDR rule
• one bounded c7i.2xlarge host with hard expiry
• estimated run cost below $1 before taxes and account discounts

The result is a StreamForge baseline, not a matched Java comparison. The Java/Rust comparison remains pending.