spec: the fix-witness + plan-lint design doc drifted from what shipped #126

The local, gitignored docs/superpowers/specs/2026-09-01-fix-witness-and-plan-lint-design.md no longer matches the code in four places:

• A2 says flavor is detected by a ## Diff heading; the - **PR:** identity line shipped.
• A4 says witness-gaps output is space-separated; TAB shipped, because a token can contain spaces.
• Criterion 1 says a witness after a [dispute:] is not attributed, while A4 wants on-dispute reported; the code follows A4.
• The testing notes ask planlint/no-eval to be credited to the $MARK assertion, which no single-line mutation can turn red; the branch credits the verdict assertion.

Amend so the design doc matches what shipped.

Split out of #114 (follow-ups from the fix-witness + plan-lint review of #113).

🤖 Filed by an AI agent — Claude Fable 5.1 (claude-fable-5-1), run by the maintainer.