Add happy-server package

[Copilot]

Adds the backend server component for the Happy Coder ecosystem to complement the existing happy-coder CLI package.

Implementation

• Package definition (packages/happy-server/)

  • Uses Yarn with fetchYarnDeps for dependency management
  • Runs TypeScript source via tsx without compilation
  • Uses makeWrapper for clean wrapper generation with proper environment setup
  • Tracks main branch commits (no releases yet) via --version=branch in nix-update-args

• Metadata

  • Version: 0-unstable-2025-11-28 (commit 84ed027)
  • License: MIT
  • Source provenance: fromSource

Usage

nix run github:numtide/llm-agents.nix#happy-server

Note: Server requires PostgreSQL, Redis, and S3 setup before running. See upstream docs.

Original prompt

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This section details on the original issue you should resolve

<issue_title>happy-server</issue_title>
<issue_description>we already support the happy-cli, but there is also a happy-server: https://github.com/slopus/happy-server</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes happy-server #1278

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[Mic92]

@copilot address the comments.