feat: Add optional localhost access for local development

[MuncleUscles]

Summary

Enables developers to allow GenLayer contracts to make HTTP requests to localhost and internal hosts (e.g., local Anvil/Hardhat nodes) during local development.

Key design decisions:

• Default behavior remains production-safe (no localhost access)
• Local dev requires explicit opt-in by copying the example file
• Uses standard Docker Compose override pattern (no wrapper scripts needed)
• Cross-platform support via extra_hosts for Linux compatibility

Usage

cp docker-compose.override.yml.example docker-compose.override.yml
docker compose up -d

Files

• docker-compose.override.yml.example - Template showing how to enable localhost access
• config-overrides.example/genvm-module-web.yaml - GenVM config with always_allow_hosts populated
• .gitignore - Excludes user's local override files from version control

Test plan

• Verified GenLayer contracts can reach host.docker.internal:8545 (Anvil) after copying override
• Verified default behavior (no override file) blocks localhost access

Summary by CodeRabbit

Release Notes

• Chores
  • Added example configuration files to facilitate local development environment setup
  • Updated .gitignore to exclude local development override files from version control

[coderabbitai]

📝 Walkthrough

Walkthrough

Three new configuration example files and updated .gitignore entries are introduced to support local development workflows. These additions provide templates for docker-compose overrides and GenVM module configuration, while marking override directories for git exclusion.

Changes

Cohort / File(s)	Summary
Local Development Configuration Examples docker-compose.override.yml.example, config-overrides.example/genvm-module-web.yaml	Example configuration files for local development setup. Docker Compose override defines service volume mounts and host networking (via extra_hosts). GenVM Web Module config specifies localhost networking, Firefox headless session, VM/Lua paths, signer settings, and always-allowed hosts.
Gitignore Updates .gitignore	Added exclusions for docker-compose.override.yml and config-overrides/ directory to prevent local override files from being version controlled.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 Local configs now have a home,
No more versioned override roam,
Examples bright for docker's ways,
GenVM Web through headless maze,
Dev machines rejoice and play! 🎉

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding optional localhost access for local development, which accurately reflects the purpose of the changeset.
Description check	✅ Passed	The description provides good context but lacks some template sections like 'Fixes #issue-number', 'Decisions made', and 'Reviewing tips'; however, it covers the essential information about what changed and why.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/localhost-dev-access

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[github-actions]

🎉 This PR is included in version 0.111.0 🎉

The release is available on GitHub release

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