Fix architecture diagram card spacing

[kabudu]

Summary

• widen authority, evaluation, and result cards without shrinking typography
• preserve the shared accessible SVG and responsive horizontal navigation
• document M69 and the user-visible fix

Validation

• ./scripts/ci-local.sh — passed at 2463be0
• python3 scripts/build-pages-site.py — passed
• python3 scripts/validate-pages-site.py — passed
• browser-rendered text bounds — minimum right-side clearance: source 28.9 px, evaluation 27.9 px, output 57.8 px, evidence 61.2 px
• desktop browser visual inspection — no text/border intersections

[kabudu]

Reviewed exact head 2463be063f848f6734d36bdb2001a182fe57621a. Complete remote diff inspected; no review comments or unresolved threads. Hosted portable passed (run 31327597635). Final ./scripts/ci-local.sh passed at the clean exact PR head, including public-history privacy, Pages, adversarial, lifecycle, reproducibility, Kubernetes, OpenTofu, Redis, PostgreSQL, and HTTP qualifications.

[kabudu]

Merged as privacy-safe local squash commit 12aaf3a after reviewing and validating exact PR head 2463be0.