Publish dev formulae for sourceos-devtools and agent-term

[mdheller]

Context

The Mac-first proof path needs Homebrew installation for the local operator surface:

• sourceosctl from SourceOS-Linux/sourceos-devtools
• agent-term from SourceOS-Linux/agent-term
• existing prophet facade should delegate to both

The tap already lists sourceos-devtools as pending, and the SourceOS Agent Machine work makes this urgent for the M2 proof path.

Scope

Add dev formulae:

brew install sourceos-devtools
brew install agent-term

The formulae should install binaries:

sourceosctl
agent-term

Requirements

• Build from main branch for dev formulae, consistent with current tap convention.
• Include basic test do blocks that execute --help or equivalent read-only commands.
• Do not bundle secrets, tokens, credentials, or device-local config.
• Document Podman as an external runtime dependency for Agent Machine flows, not as something this tap mutates automatically.
• Update README current/pending formulae tables.

Acceptance criteria

• brew audit --strict --online guidance documented for local checks where feasible.
• brew test sourceos-devtools and brew test agent-term pass on macOS.
• prophet-cli README can point users to the tap install path for all required local tools.

Non-goals

• Do not install or initialize Podman machines from the formula itself.
• Do not modify host system settings from Homebrew postinstall.
• Do not write user profiles or mount directories during install.