docs(website): correct the IsObject exact cost in the type-functions guide

[unional]

Closes #701. This fixes the last gap in that issue.

Audit of #701's "Done when" list against main

Bullet	Status	Evidence
Filter<Array<…>, F> applies F, with specs	✅	#703. Filter/KeepMatch<Array<1 | { a: 1 }>, IsObject.$Fn> gives Array<{ a: 1 }>, and a no-match gives never[], on TS 5.4, 6.0 and 7. Specs are in array_plus.filter.spec.ts and filter.spec.ts.
All 62 predicates in part 2 have .$Fn, with a spec each	✅	#704. A probe applying $Fn.Apply<X.$Fn, 1> to all 62 compiles on TS 5.4 and 7, and every one has a X.$Fn spec in its own spec file. 63 one-input $Fns have the IsObject.$Fn shape (the 62 plus IsObject).
Two-input predicates have .$Fn in the proposed shape	✅	#705. Equal, Assignable and NotAssignable use $Fn<B, $O>, and HasKey and IsOptionalKey use $Fn<K, $O>. All three examples from the issue compile.
Guide support table and predicate list updated	✅	The table marks every collection type ✅ for arrays. The predicate list matches the code.
Instantiation cost re-measured with bench-instantiations.mjs	⚠️ → fixed here	I re-ran the script on TS 6.0 and 7. Most of the guide's figures reproduce: +10 for plain-type dispatch, IsObject ≈ 24, ≈ 6 per entry, IsNotString.$Fn 973 vs $Fn.Not<IsString.$Fn> 1090, and an IsNot… saving of ≈ 117. IsObject with exact now measures 153, at both 100 and 300 uses, but the guide said about 140, a figure carried over from #700.

Change

• Change the guide's IsObject + exact figure from about 140 to about 150.
• Name the bench script as the source of the figures.

Only the private website app changes, so there is no changeset.

pnpm verify passes.

🤖 Generated with Claude Code

[changeset-bot]

⚠️ No Changeset found

Latest commit: ae2c53f

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (26d0d66) to head (ae2c53f).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #706   +/-   ##
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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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