chore: Add IFT relay to demo

[dianab-cl]

No description provided.

[linear-code]

FOU-1343

[greptile-apps]

Greptile Summary

The PR expands the Besu-to-Besu example into an end-to-end IFT relay demo with KMS-backed signers, standalone attestors, deployment automation, and optional round trips.

• Adds Compose services and configuration for KMS, two attestors, a relayer, and deployment tooling.
• Automates IBC, GMP, IFT, bridge deployment, transfer submission, relaying, and balance verification.
• Adds restart-aware demo orchestration and extensive operational documentation.

Confidence Score: 4/5

The PR should not merge until relayer readiness is tied to completed service startup rather than an open TCP port.

The server binds port 3000 before the relay dispatch loop starts, but Compose considers that TCP listener healthy and allows the transfer phase to invoke the relay API immediately.

Files Needing Attention: examples/besu-to-besu/docker-compose.yml, examples/besu-to-besu/lib/link.sh

Important Files Changed

Filename	Overview
examples/besu-to-besu/lib/link.sh	Adds deployment and IFT relay orchestration, including the Compose readiness wait, but immediate relay still depends on an insufficient TCP-only health signal.
examples/besu-to-besu/docker-compose.yml	Adds the complete Link service topology; the relayer healthcheck does not establish application readiness.
examples/besu-to-besu/setup.sh	Reworks the example into a five-phase end-to-end relay demo with a round-trip fast path.
examples/besu-to-besu/README.md	Documents the new architecture, deployment flow, signing model, transfer behavior, and troubleshooting guidance.

Sequence Diagram

sequenceDiagram
  participant Setup as setup.sh
  participant Compose
  participant RelayerServer as Relayer listener
  participant Dispatcher as Relay dispatcher
  participant Transfer as Transfer phase
  Setup->>Compose: up -d --wait
  Compose->>RelayerServer: Start container
  RelayerServer->>RelayerServer: Bind port 3000
  Compose->>RelayerServer: nc -z healthcheck
  RelayerServer-->>Compose: TCP connection succeeds
  Compose-->>Setup: Services healthy
  Setup->>Transfer: Begin transfer
  Transfer->>RelayerServer: Relay RPC
  RelayerServer->>Dispatcher: Dispatch request
  Note over RelayerServer,Dispatcher: Dispatcher startup occurs after the listener binds

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_{Reviews (2): Last reviewed commit: "Merge branch 'main' into diana/fou-1343-..." | Re-trigger Greptile}

[dianab-cl]

@greptile review