Generalize Tate algebras to positive polyradii

[dagurtomas]

Goal

Generalize the strict unit-polyradius Tate algebra API to finite positive polyradii while preserving the existing unit-radius declarations.

Possible layers:

• weighted restricted power series and weighted Gauss norms;
• nonarchimedean normed-ring and completeness instances;
• multiplicativity under appropriate value-group hypotheses;
• universal properties for tuples satisfying the radius bounds;
• comparison with the existing unit-polyradius algebra when all radii equal 1.

Keep this in separate production modules initially; do not change comparator declarations until the API is stable.

This work is independent of the current global-space and Tate-acyclicity branches. Comment claimed before starting.