Support core-schema integer and float forms

[MariusStorhaug]

Why

YAML 1.2.2 core schema recognises integer and float forms beyond plain base-10, but the current parser only resolves base-10 integers and standard floats, so documents using octal, hex, or special float literals parse incorrectly.

What

Recognise the full core-schema scalar forms: octal (0o...) and hex (0x...) integers, and .inf/.nan floats (with sign and case variants). ConvertTo-Yaml should round-trip [double]::PositiveInfinity, NegativeInfinity, and NaN to their canonical .inf / -.inf / .nan forms, and emit integers in base-10.

Spec examples covered

• Example 2.19 — Integers
• Example 2.20 — Floating Point

[MariusStorhaug]

What changed: Reformatted the issue body to the MSXOrg Issue Format — a local Why plus an outcome-level What/acceptance criteria. Removed the Technical Decisions and Implementation Plan sections (and other implementation-tradeoff notes).
Why: Issue bodies should state local purpose and observable outcome without leaking implementation detail into the outcome-level description; durable technical decisions belong in the PR/design, not the tracking issue.
Follow-up: None.