style(lang): British English compliance and AI-tell removal across UI strings

[Bissbert]

Summary

• AmE → BrE spelling swaps across 26 components and pages: colour/colour-by-form/colourless/coloured (ChelseaFilter, DichroscopeResults, SpectroscopeCalculator, LabTools, OpticalTools, DispersionCalculator, TreatmentDetection); visualisation/visualisation (12 files: index.astro, og-image.astro, docs/*.astro, Footer.astro, FamilyModal.tsx, MineralModal.tsx); colour in API param descriptions (crystal-renderer.astro, crystal-geometry.astro)
• Em-dash replacement — before/after counts per hot-spot:
  • HardnessReference.tsx: 21 em-dashes → colons/semicolons
  • about.astro: 5 em-dashes → spaced en-dashes, colons, or parentheses
  • CriticalAngleCalc.tsx: 3 em-dashes → parentheses
  • LearnQuizWidget.tsx: 1 user-visible em-dash → semicolon
  • DispersionCalculator.tsx: 1 em-dash → parentheses
  • SpectroscopeCalculator.tsx: 1 em-dash → spaced en-dash
  • study/review.astro: 1 em-dash → colon
  • _dev/study-components.astro: 1 em-dash → colon
  • BaseLayout.astro: 2 title em-dashes → spaced en-dashes
  • Quiz YAML bank (63 files): ~280 spaced em-dashes → spaced en-dashes in rationale prose; option-text Pattern X — description → Pattern X: description throughout equipment/ri-reading-*.yaml
• AI-tell phrase removal: "dive in" (learn/index.astro), "Dramatic color shift" → "Striking colour shift" (DichroscopeResults.tsx)
• TreatmentDetection.tsx hot-spot fully resolved (8 additional colour/centre swaps on top of 12 pre-staged)

Verification gates

• npx astro build: 912 pages, no errors
• npx tsc --noEmit: pre-existing errors in db.ts/sanitize-svg.ts only (unchanged from base branch)
• AmE grep: zero hits
• Em-dash grep: zero hits in edited files (one '—' N/A placeholder in HardnessReference preserved intentionally)
• AI-tell grep: zero hits

Test plan

• Review AmE → BrE diff in each component for correctness
• Confirm CSS class names (transition-colors, text-color, bg-*) are untouched
• Confirm API param names (color_by_form, face_color) are untouched in code blocks
• Spot-check quiz YAML options for readable punctuation after em-dash → en-dash swap
• Verify build passes in CI

🤖 Generated with Claude Code

[github-actions]

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