Add Oh My Pi 18.2.4

[nullStack65]

What this adds

Oh My Pi (omp) is an open-source (MIT) coding agent. It ships a standards-based ACP server over stdio, launched as omp acp.

This PR registers that server so generic ACP clients can install and launch Oh My Pi directly from the registry. No client-specific integration is required, and no part of this entry is tailored to a particular client.

Distribution

A single binary distribution built from the official v18.2.4 GitHub release. The released artifacts are self-contained raw executables, so no npm/Bun runtime is imposed on clients.

Registry target	Release asset
darwin-aarch64	omp-darwin-arm64
darwin-x86_64	omp-darwin-x64
linux-aarch64	omp-linux-arm64
linux-x86_64	omp-linux-x64
windows-aarch64	omp-windows-arm64.exe
windows-x86_64	omp-windows-x64.exe

• cmd is ./omp (./omp.exe on Windows) with args: ["acp"], i.e. omp acp.
• Every declared sha256 was copied from the release's official SHA256SUMS.txt and cross-checked against the GitHub release asset digests; all six match.

Authentication

Oh My Pi's initialize response advertises one auth method (id: "agent", type agent) which uses whatever provider credentials are already configured on the user's machine. No credentials or auth state are embedded in this entry.

Validation

• build_registry.py --dry-run: schema, id/version/distribution checks, URL accessibility, and icon validation all pass.
• Registry workflow tests and ruff check / ruff format --check: pass.
• verify_agents.py --auth-check --agent oh-my-pi (macOS, darwin-x86_64): downloads the declared asset, accepts the declared SHA-256, extracts, resolves ./omp, launches omp acp, and receives authMethods — passes.
• Zero-inference smoke test (no provider calls, no model prompt): omp --version reports omp/18.2.4; initialize is answered on protocol version 1 with agentInfo: oh-my-pi 18.2.4; the process exits cleanly (code 0) when the client closes stdin.

The icon is derived from Oh My Pi's canonical Pi-glyph mark (as used at omp.sh and in the repository), reduced to the required 16x16 monochrome currentColor SVG.