feat(type-plus): add .$Fn to every one-input predicate

[unional]

Part 2 of #701. Part 1 (the ArrayPlus.Filter bug) is in #703. Part 3 (the two-input predicates) is waiting on a decision about parameter order.

Changes

• Added .$Fn<$O> to all 62 one-input predicates listed in feat(type-plus): complete type-function ($Fn) support across predicates and ArrayPlus.Filter #701. It has the same shape as IsObject.$Fn: readonly out: IsX<this['in'], $O>, with $O checked by $StrictOptions.
  • The list covers the special-type, primitive, numeric and structure predicates, HasNull, HasUndefined, HasVoid, and every IsNot… counterpart, including IsNotObject.
  • IsNotX.$Fn wraps IsNotX directly, which is already the cheap inverse. It does not go through $Fn.Not.
• Each .$Fn has a TSDoc $Fn.Apply example. The example is pinned in the predicate's existing spec, under a describe('X.$Fn') block.
• Updated guides/type-functions.mdx: the predicate list, two examples (checked against the compiler), and a cost note on IsNot… vs $Fn.Not.
• scripts/bench-instantiations.mjs: collection() now takes extra imports, and there are new Filter benches.
• Added a minor changeset.

Instantiation cost

Per TuplePlus.Filter call on a distinct 10-entry tuple, 100 uses:

Type	TS 6.0	TS 7
Filter+object	679.7	679.7
Filter+IsObject.$Fn	967.3	967.3
Filter+IsNotObject.$Fn	963.0	963.5
Filter+Not<IsObject.$Fn>	1079.6	1079.7
Filter+IsString.$Fn	952.9	953.5
Filter+IsNotString.$Fn	972.2	972.7
Filter+Not<IsString.$Fn>	1088.9	1089.5
Filter+IsInteger.$Fn	2210.1	2213.0
Filter+IsUnion.$Fn	877.5	878.0
Filter+HasNull.$Fn	1315.0	1316.3

An IsNot… counterpart saves about 110 instantiations per call (about 10%) compared with $Fn.Not.

Verification

• Type tests pass on all five compilers: pnpm --filter type-plus test:type.
• test:errors matches the snapshot on all five compilers.
• pnpm verify passes. Locally, check flagged only an untracked harness file that is not part of this PR.

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: cf966e7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
type-plus	Minor

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (302d5de) to head (cf966e7).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #704   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           43        43           
  Lines          231       231           
  Branches        51        51           
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  Hits           231       231           

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