Add primitive arrays column wrappers

Primitive array columns are required for optimized big-data applications. It is also possible to add numerical DataFrame integration with MultiK or KMath.

No files, tests, or entry points are named; start by locating the existing DataFrame column and wrapper abstractions and reviewing how primitive values are represented. Define the required primitive-array column behavior and determine whether MultiK or KMath integration is in scope before implementation; done means the agreed wrappers and numerical integration requirements are covered.

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