docs: clarify where implementations read 4.1 differently

[johannschopplich]

Wording fixes and fixtures for places where the ports read 4.1 differently. Every change pins what the 4.1 text already says, so this is a 4.1.x patch with no behavior change.

• Contradictions – two root scalars are an error in any mode in §5 too, and neither the non-strict leniency for trailing content nor the skip for over-indented lines covers scalar lines.
• Gaps – surrogate escapes are rejected in pairs too, any other array in list form nests as a list, spaces may separate a quoted key from its colon, field entries are trimmed, and only one CR before the line end belongs to the terminator.
• Fixtures – 29 cases, one or more per change, plus rules that had no fixture yet. The lone-CR case from test: cover the fixture gaps found in the port reviews #63 goes, since the double-CR case covers it.

Stacked on #63. Two new cases fail the reference until toon-format/toon#355 lands: "a" : 1 and a bare token after a root array in non-strict mode.