chore: Update localnet TEE script for Rust launcher

[barakeinav1]

closes #2523
This PR updates the existing localnet TEE script to the new RUST launcher and toml input it uses.

Summary

• Add node.conf.localnet.toml.tpl — TOML config template for the Rust tee-launcher, matching the Config struct with [launcher_config], [mpc_node_config], and subsections
• Add set-localnet-env.sh — convenience script to set all required env vars for a localnet deploy run

These are new files only — existing scripts are not modified.

Test plan

• Verify template renders valid TOML via envsubst
• Source set-localnet-env.sh and run deploy-tee-localnet.sh

[claude]

Review

No critical issues found. The PR adds two new localnet-only config/env files with no changes to existing code.

Minor note (non-blocking): set-localnet-env.sh:14 has MACHINE_IP=51.68.219.1 and set-localnet-env.sh:15 has BASE_PATH=/mnt/data/barak/dstack which appear to be developer-specific values. These won't cause bugs but may confuse other users of the template. Consider adding a comment noting these should be customized per-environment, or using placeholder values.

✅ Approved — straightforward addition of localnet deployment templates with no production code changes.

[netrome]

Approving since these are standalone scripts not tied to production. I haven't reviewed them given the size of the PR and my limited time today.