v0.3

Everything approved now sits in the solution folder's spec/ folder, and the solution has a name of its own. The spec names its items with references, paths that walk spec/ such as requirements.remind.at-most-weekly, and another repo points at the same items by putting the solution's name and a colon in front. Specs written against v0.2 stay pinned to v0.2 until they're revised.

solution-planner.zip and solution-planner.skill are the same zip, with the solution-planner folder inside. Use whichever your agent takes.