nsdata/v2 package

Package nsdata is the registry — the records behind every name.

IT IS REPLACEABLE NOW, and that changes what every comment below means.

Until this generation the vault held ownership as well as records, which made it the one realm that could never be redeployed: a "new nsdata" was an empty registry and everybody's names with it. So everything here was written as if it would ship forever — no constants, no policy, no display code — and the comments say "can never be replaced" throughout.

Ownership has moved to nsnft, the small frozen token realm. This realm keeps records — dates, the frozen bit, TTL, profile data, reverse resolution, pricing globals, domains — and reads every owner from the ledger rather than storing one. Replacing it is a new package plus one Trust call on nsnft; no token moves, no holder notices. The integration address the outside world keeps is nsnft's, not this one's.

The two old rules still hold, for a better reason than before:

1. NOTHING IS A CONSTANT. Term length, grace period, size caps — all settable. Not because a mistake would be permanent any more, but because a registry that needs a redeploy to change a number is a registry that gets redeployed carelessly.

2. THE REGISTRY STORES, IT DOES NOT DECIDE. Pricing math, validation, what a profile field means — all of it lives in nslogic. Anything this realm "knows" is a rule that needs a migration to change.

Rule 2 is why Domain and Name carry an `extra` tree instead of a growing list of typed fields.