[MrSkwiggs]

Part of #879. Ignite will be installable from a maintainer-owned tap, twostraws/homebrew-ignite:

brew tap twostraws/ignite
brew install ignite-swift

The formula is named ignite-swift because homebrew-core already has an unrelated ignite formula. The installed command is still ignite.

Changes

• Server script lookup (RunCommand.swift): ignite run used to find ignite-server.py from argv[0]. That breaks when ignite is launched from PATH (no slash in argv[0]). It now checks three places: next to the executable, next to the executable with symlinks resolved, and in a sibling libexec/ folder. The executable is found with Bundle.main.executableURL, falling back to argv[0]. make install keeps working, and a future version of the formula can move the script out of bin/ into libexec/. The script path is now quoted in the shell command, and the "missing script" message mentions brew reinstall.
• Release workflow (.github/workflows/release.yml): runs on version tags such as 0.7.2.
  1. It creates a GitHub Release with generated notes, unless the Release already exists.
  2. It computes the source tarball's sha256, then opens a PR on twostraws/homebrew-ignite that updates Formula/ignite-swift.rb. The tap's brew test-bot builds bottles on that PR, and a maintainer adds the pr-pull label to publish.
• README: adds Homebrew install instructions next to the existing make install steps.

Before merging

• Add a HOMEBREW_TAP_TOKEN repository secret: a fine-grained token with access to twostraws/homebrew-ignite only, with Contents and Pull requests set to read and write. Without it, the bump job fails with a clear error, but the Release is still created.
• Merge the tap's initial formula PR first, so the README instructions work as soon as this lands.

Testing

• CI builds and runs the test suite.
• The workflow YAML parses. The formula-editing commands were run against a copy of the formula with a sample bottle block: the URL and sha256 lines update, and the stale bottle block is removed.
• The 0.7.1 tarball sha256 in the tap formula was checked against GitHub.