[do-io]

README only, no code changes.

• Title is now "Odden Mail Builder (getodden/mail)" instead of "Laravel Mail Builder".
• The tests badge points at a workflow that no longer runs on pushes, so it is replaced by Packagist version, license and PHP badges.
• A short pitch under the title: what you build, what it compiles to, and that the compiler is plain PHP with no Node step at send time (checked: nothing in src/ shells out, and the editor ships prebuilt in resources/dist).
• A "Sending, lists and campaigns" section says what this package does not do and where that comes from.

Not in this PR: screenshots or a demo (next), the GitHub homepage setting (still dophp.dev), and a docs page on odden.io.

🤖 Generated with Claude Code