fix(toml): emit TOML literals for Infinity/NaN/Date in arrays

[spokodev]

Primitive and mixed array stringification went through code paths that produced invalid TOML for non-finite numbers and Date values. The issue author flagged six distinct cases in #7162; this PR addresses the four with a deterministic spec-aligned fix and leaves the two null-related ones for maintainer guidance, since they are a design call.

What changed

#arrayDeclaration (primitive arrays) previously routed values through JSON.stringify, which has no representation for Infinity, -Infinity, NaN, or TOML datetime literals. #printAsInlineValue (mixed arrays) returned numbers verbatim (so Infinity printed as the JS identifier) and wrapped Dates in string quotes.

A new private helper #printPrimitive produces TOML-compliant literals for Date, string, RegExp, number (including inf/-inf/nan) and boolean. Both array paths now route primitives through it.

Behaviour for null/undefined inside arrays is unchanged - the code still throws Should never reach. The issue author flagged this as a design call (TOML has no null), so it stays as-is until maintainers decide between a clearer error message, silent skip, or another shape.

Before/after

// primitive array
stringify({x: [Infinity, -Infinity, NaN]})
// before: x = [null,null,null]
// after:  x = [inf,-inf,nan]

stringify({x: [new Date(0)]})
// before: x = [\"1970-01-01T00:00:00.000Z\"]
// after:  x = [1970-01-01T00:00:00.000]

// mixed array
stringify({x: [Infinity, -Infinity, NaN, {}]})
// before: x = [Infinity,-Infinity,NaN,{}]   (invalid TOML)
// after:  x = [inf,-inf,nan,{}]

stringify({x: [new Date(0), {}]})
// before: x = [\"1970-01-01T00:00:00.000\",{}]
// after:  x = [1970-01-01T00:00:00.000,{}]

Tests

Six new cases in toml/stringify_test.ts:

• positive: Infinity/-Infinity/NaN in primitive arrays render as inf/-inf/nan
• positive: Date in primitive arrays renders as a bare TOML datetime literal
• positive: Infinity/-Infinity/NaN in mixed arrays
• positive: Date in mixed arrays
• regression-check: finite numbers in primitive arrays keep their JSON-style representation (covers the new #printPrimitive path that replaced JSON.stringify)
• regression-check: scalar Infinity/NaN/Date declarations (not array elements) are unaffected

One existing test (stringify() handles mixed array) had a date inside a mixed inline-table that was previously emitted with quotes. The expected output is updated to the spec-aligned bare datetime literal.

`deno test --allow-all toml/` -> 689 passed, 0 failed, 111 ignored.
`deno fmt` and `deno lint` clean on the changed files.

Fixes #7162 (partial - null handling left for maintainer guidance).

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.57%. Comparing base (cdf74a8) to head (8dd582f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7163   +/-   ##
=======================================
  Coverage   94.57%   94.57%           
=======================================
  Files         636      636           
  Lines       52142    52147    +5     
  Branches     9401     9406    +5     
=======================================
+ Hits        49315    49320    +5     
  Misses       2249     2249           
  Partials      578      578           

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