feat(super-user): auto-activate via subdomain and add persistent cache

[AugustoL]

Description

Improves super user mode with two enhancements: auto-activation via the super subdomain and a persistent localStorage cache for blockchain data.

Related Issue

Closes #240, Closes #242

Type of Change

• New feature
• Bug fix
• Documentation update
• Refactoring
• Performance improvement
• Other (please describe):

Changes Made

Issue #240 — Subdomain-based super user activation

• Added super subdomain entry to src/config/subdomains.ts so super.openscan.io is recognized
• In SettingsContext.tsx, detect super subdomain on init and force isSuperUser: true

Issue #242 — Persistent storage in super user mode

• Added persistentCacheSizeMB field to UserSettings type (default: 10 MB)
• Created src/utils/persistentCache.ts — localStorage-based cache with LRU eviction, OPENSCAN_PCACHE_ prefix keys, and QuotaExceededError handling
• Created src/hooks/usePersistentCache.ts — React hook providing getCached/setCached that are no-ops when super user mode is disabled
• Added super user settings section to Settings page (cache size limit dropdown, usage display, clear button) — only visible when isSuperUser is true
• Integrated clearPersistentCache() into the existing clearAllCaches() function
• Added i18n translations for en and es

Screenshots (if applicable)

N/A — Settings section only visible when super user mode is active.

Checklist

• I have run npm run format:fix and npm run lint:fix
• I have run npm run typecheck with no errors (pre-existing errors only)
• I have run tests with npm run test:run
• I have tested my changes locally
• I have updated documentation if needed
• My code follows the project's architecture patterns

Additional Notes

The usePersistentCache hook is ready for page-level components (block, tx, address pages) to integrate — they can wrap their data fetches with getCached/setCached to persist blockchain data across sessions.

[github-actions]

🚀 Preview: https://pr-256--openscan.netlify.app
📝 Commit: 8a2cfefaf570d6880672c38cc4bdad92e50ebe75

[josealoha666]

🧪 Persistent Cache — Test Report

Preview: pr-256--openscan.netlify.app | Commit: 8a2cfef

✅ What works

Test	Result
Super User Mode toggle	✅ Enables/disables correctly from navbar
Settings UI — Cache Size dropdown	✅ 5/10/25/50/100 MB options, persists on save
Settings UI — Usage display	✅ Real-time "Using X.XX MB of Y MB"
Settings UI — Clear Cache button	✅ Clears all OPENSCAN_PCACHE_ entries, UI updates to 0.00 MB
localStorage persistence	✅ Data survives page reload/navigation
Cache key format	✅ OPENSCAN_PCACHE_{networkId}:{type}:{identifier}
Cache entry structure	✅ data, storedAt, lastAccessedAt, version fields correct
Size calculation	✅ Matches actual localStorage bytes (UTF-16 × 2)
clearAllCaches() integration	✅ Persistent cache included in general "Clear Cache"
Cache size limit change	✅ Dropdown updates persistentCacheSizeMB in settings, reflected in UI

⚠️ Cache not wired to data fetching yet

The usePersistentCache hook exists and works correctly, but no component calls it. Browsing network pages, block detail, tx detail, and address pages produces zero OPENSCAN_PCACHE_ entries in localStorage.

This is acknowledged in the PR description ("ready for page-level components to integrate"), but it means the persistent cache feature is not functional end-to-end for users yet — Settings will always show "Using 0.00 MB".

🔧 Test methodology

1. Opened PR preview, enabled Super User Mode
2. Navigated to Settings → verified cache section visible with correct defaults
3. Browsed Ethereum Mainnet, block pages, tx pages → checked localStorage for OPENSCAN_PCACHE_ keys (found 0)
4. Manually wrote test entries to localStorage via console → verified Settings UI reflected correct size (1.91 MB)
5. Tested Clear Cache button → entries cleared, UI updated to 0.00 MB
6. Wrote 5 entries, reloaded page → data persisted correctly
7. Changed cache size limit to 5 MB, saved → setting persisted

Verdict

Infrastructure: solid ✅ — The cache utilities, hook, settings UI, and LRU eviction logic are well-implemented.
Integration: missing — Hook needs to be wired into data-fetching components for the feature to be user-facing.

Recommendation: ship as infra-only and wire the hook in a follow-up PR, or add basic integration to at least one data path (e.g., block detail) before merge.