Summary

Move Homebrew, deb, and snap gateway package defaults into gateway.toml now that the gateway supports TOML configuration. New installs create the canonical package gateway.toml directly and no longer create a package gateway.env; existing env files are still read so gateway OPENSHELL_* variables continue to take precedence at launch.

Related Issue

N/A

Changes

• Added a shared package config generator in deploy/common/init-gateway-config.sh for deb, snap, and generated Homebrew formulas.
• Simplified generation so packages write deterministic canonical TOML instead of interpolating env vars into the config.
• Avoid selecting a compute driver in generated package TOML; users can select one through --drivers, OPENSHELL_DRIVERS, or edited TOML, otherwise gateway auto-detection applies.
• Updated Homebrew formula generation to embed the shared helper, create #{var}/openshell/gateway.toml, and keep reading existing gateway.env files before launching.
• Updated deb packaging to install the shared helper, create %S/openshell/gateway/config.toml, and preserve the systemd EnvironmentFile compatibility path.
• Updated snap packaging and wrapper to create $SNAP_COMMON/gateway.toml through the shared helper while still honoring launch env such as OPENSHELL_GATEWAY_CONFIG and OPENSHELL_DB_URL.
• Refreshed package docs/man pages and release formula tests.

Testing

• mise run pre-commit passes
• uv run pytest python/openshell/release_formula_test.py
• sh -n deploy/common/init-gateway-config.sh
• sh -n deploy/snap/bin/openshell-gateway-wrapper
• bash -n tasks/scripts/package-deb.sh
• bash -n tasks/scripts/package-snap.sh
• generated deb/Homebrew/snap TOML parse smokes
• systemd-analyze --user verify not run; systemd-analyze is not installed on this host
• E2E tests added/updated (not applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)