Templates and storage attachment

[mwindower]

Description

Rename templates to PoC/Production, drop the topology variant, attach storage at the exits
Three cleanups to the plan model and its editor:

• The Starter template is really a proof of concept and Redundant is what a production install looks like, so they are now PoC and Production.
• Plan.topology (single-zone | metro | multisite) was a label nothing derived from; its only effect was a warning restating the partition count. The field, its store action, the radio group and the warning are gone. Old plan files still import: PlanSchema strips the unknown key, so the format version stays at 1.
• External networks of kind storage no longer enter through the internet routers. They attach at the partition's storage leaves, or at its exit switches when it has none (attachesAtStorageLeaves() is the single source of that rule, used by the derivation and by the diagram, which draws the capsule over the storage box). filterTopology() drops an external network whose attachment points all fell away, so central mode no longer floats a storage capsule.

Used AI-Tools ✨

• Claude Opus 5.5