fix: align public route interactions and navigation

[Gnaroshi]

Summary

• fix Reading overview/hash current-state transitions, locale query/hash preservation, canonical internal paths, and evidence-gated indexing
• add local-only three-pass checklist, Research anchor navigation with accessible diagram zoom, and consistent Home/Now freshness links
• reduce duplicate project card links and add project section navigation, stable heading permalinks, and denser long-form project structure
• strengthen negative interaction invariants and EN/KO viewport coverage down to 320x568

Local verification

• npm run content:check
• npm run check
• npm run build
• npm run check:i18n
• npm run check:public-tone
• npm run check:launch-content
• npm run check:links
• npm run check:project-readiness
• npm run check:project-copy
• npm run media:check
• npm run test:smoke (5 passed)
• npm run test:feed-contract (11 valid fixtures, 6 expected rejection fixtures)
• npm run test:e2e (172 passed, 5 fixture-dependent skipped)
• npm run test:a11y (55 passed)
• npm run test:visual (52 passed)
• all-route top-position visual recapture (14 passed)
• npm run test:performance (7 passed)

GitHub Actions were not queried or re-run as part of this task.