docs: switch to qml info generated help files

[juliuspfadt]

Recovers 60846e9, originally on the contourPlot branch (PR #484, closed).
That PR was superseded by #491 (contourPlot-clean), which was rebuilt from
scratch and dropped this commit — so the help migration never landed.

• remove 18 .md files + images from inst/help/
• add info: / infoBottom: to all 23 QML files

Master edited the .md files after the original branch point (#475, #485);
those edits are ported into the QML info text rather than lost:

• SKF/Dodson references removed (8 files); SKF QT 9 → AIAG ref in the two DOE files
• "predictors" → "factors" in doeAnalysis.qml info text (matches existing UI labels)
• "ANOVA" → "Analysis of Variance" in msaGaugeRR / msaGaugeRRnonrep
• pooled within-SD guidance added to the R-bar/S-bar/Pooled dropdown in processCapabilityStudies.qml
• Z.bench (ST)/(LT) text already equivalent — unchanged

No option names, values or defaults changed; diff is info:/label: text only.
qmllint clean. Full suite: 1195 tests, 0 failed, 0 errors, 5 skipped.

🤖 Generated with Claude Code