feat: switch compute-node registration to SIWE wallet flow and drop NODE_URL

[tatiesmars]

Summary

• Remove the NODE_URL requirement from compute-node config and examples; inbound HTTP registration is now legacy-only.
• Update node-registration to request SIWE metadata, build an EIP‑191 message, and register via /internal/v1/nodes/register-wallet using the derived wallet address.
• Refresh registration on the configured interval, and simplify status handling (no healthcheck TTL).
• Update README docs and tests to match the new SIWE wallet registration flow.

[Copilot]

Pull request overview

This PR removes the requirement for compute nodes to expose a public URL, migrating from callback-based registration to a wallet-based SIWE (Sign-In With Ethereum) authentication flow.

Changes:

• Replaced timestamp-based registration with SIWE message signing using EIP-191
• Removed node_url field from configuration and registration requests
• Added new cryptographic functions for Ethereum address derivation and EIP-191 signing
• Simplified registration loop by removing healthcheck callback logic

Reviewed changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
core/node-registration/src/register.rs	Replaced timestamp-based registration with SIWE flow; removed node_url parameter and healthcheck TTL logic
core/node-registration/src/crypto.rs	Added derive_eth_address and sign_eip191_recoverable_hex functions for Ethereum wallet operations
core/node-registration/README.md	Updated documentation to reflect SIWE-based registration and removed references to URL requirements
core/compute-node/tests/engine_dms_flow.rs	Removed node_url from test configurations
core/compute-node/tests/config_tests.rs	Updated tests to remove NODE_URL environment variable checks
core/compute-node/src/http.rs	Updated comments to clarify legacy nature of HTTP router
core/compute-node/src/engine.rs	Updated log message to remove reference to callback
core/compute-node/src/dds/register.rs	Removed node_url from registration settings and related logic
core/compute-node/src/config.rs	Removed NODE_URL environment variable requirement
core/compute-node/src/auth/siwe_after_registration.rs	Removed node_url from test configuration
core/compute-node/README.md	Updated documentation to reflect URL-less registration flow
core/compute-node-runner-api/examples/hello-runner/src/main.rs	Removed HTTP server setup code
core/compute-node-runner-api/examples/hello-runner/Cargo.toml	Removed axum dependency
core/compute-node-runner-api/examples/hello-runner/.env.example	Removed NODE_URL from environment example

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