Scribe v2.1.1 - Type Accessor Fixes

A types and tooling release. Three members of the server API were missing from the type
Scribe.Server hands back, so calling them from a strict-mode script was a type error even though
they worked at runtime. It also raises the template size at which Luau gives up type-checking your
game entirely.

Added

• Scribe.ExchangeableSpec is exported, and the Exchangeable option is now declared on
  ScribeOptions. The option always worked, and Luau never rejected it because it does not check
  extra keys in an options literal, but naming the type means a game can build the allowlist as a
  typed table separately from the options table and get completion on Path, Kind, Count,
  Identity and Ignore.

Fixed

• Data.PromptPurchase, Data.Exchange and Data.Stop were missing from the type Scribe.Server
  returns, so a strict-mode script calling any of them reported the key as not found in the Data
  table while the call itself worked at runtime. Data.Exchange is now typed in full, including
  what Open hands back. Data.PromptPurchase and Data.Exchange were new in 2.1.0; Data.Stop
  had been missing since before 2.0.0.

Changed

• A template can now be roughly three times larger before Luau reports "Code is too complex to
  typecheck" at the Scribe(...) call and silently stops checking the file. The accessor type is
  built once per distinct shape instead of once per field, which matters because a template repeats
  declarators heavily and Luau treats each one as a separate type. Measured on a template of mixed
  records and containers, the limit moved from 12 roots to over 32; a template whose roots are all
  structurally different still gains about half again. Nothing about the types changes: every
  diagnostic is identical, across every declarator.

• Scribe.OpenExchange declares State as "Claimed" | "Staked" | "Delivering" rather than
  string, so a game can narrow on it. Assigning what Data.Exchange.Open returns to a
  { Scribe.OpenExchange } did not type-check before this.

Documentation

• The leaderboards guide covers Roblox's built-in leaderboard UI, which renders a persistent
  leaderboard with no UI code by reading an OrderedDataStore directly. It needs a store name of
  LB_<BoardName> and a key template of {UserId}. A Scribe.Big board cannot be shown that
  way, because it stores a packed integer rather than the score, and the guide says so.

• The big numbers and containers guides record that a Scribe.Big declared as a field of a
  container's element shape puts a template past the Luau type solver's budget, so the file stops
  being type-checked. It is a type-checking limit only and the code runs correctly either way. The
  guides give the shapes that do fit, including a container whose element is the big itself.

Full Changelog: v2.1.0...v2.1.1