feat(apps): add mobile phone home-screen "Apps" tab

[MichaelTaylor3d]

Summary

Adds a top-level Apps tab that renders the curated dApp catalog as a phone-home-screen icon grid — rounded app icons + short name labels, tap an icon to open the dApp directly (a small "i" affordance opens the existing detail page). Mobile shows the icons in a comfortable, tap-friendly grid that reads like a real phone home screen; desktop scales the same grid up, clustered/centered rather than stretched full-width. A labelled Store/Apps view-tabs nav switches between the existing store shelf and the new tab; both are real routed pages (/ and /apps), so /apps stays crawlable, bookmarkable, and shareable.

Reuses the existing catalog data + AppIcon component unmodified (no new metadata model) — see blast radius below for why AppIcon itself was left untouched. /apps gets its own prerendered SEO head (title/canonical/OG/Twitter), a CloudFront viewer-request rewrite rule, a sitemap.xml + llms.txt entry, a PWA manifest shortcut, and a check-dist audit entry, mirroring the existing per-app-page contract. i18n keys added across all 14 locales.

Closes DIG-Network/dig_ecosystem#51.

Blast radius (gitnexus, §2.0)

• impact(AppIcon, upstream) → CRITICAL, 9 impacted symbols across 7 execution flows / 4 modules (Store, Detail, Catalog, Components) — this is why AppTile reuses AppIcon completely unmodified and only re-skins it via CSS descendant selectors (.app-tile-icon-frame .app-icon), never touching the component itself.
• impact(parseRoute, upstream) → LOW, 0 impacted (pure classifier, additive new "apps" route kind).
• impact(App, upstream) → LOW, 1 impacted (its own entry point) — the new /apps branch is additive to the existing route switch.
• New files (AppTile, ViewTabs, AppsHomeScreen) have no prior callers — zero regression surface on existing views, confirmed by the full existing test suite staying green.

Changes

• src/lib/route.ts — new "apps" route kind (/apps), additive to the existing union.
• src/components/AppTile.tsx, src/components/ViewTabs.tsx, src/features/apps/AppsHomeScreen.tsx — new components (tested, typed, i18n'd, a11y-labelled).
• src/App.tsx — wires ViewTabs above the home/apps views; page-title effect covers /apps.
• src/styles.css — phone-home-screen grid (auto-fit fixed-width tracks so a handful of icons cluster instead of stretching), rounder "squircle" icon framing, tab pill styling, mobile breakpoints.
• scripts/prerender-apps.mjs / scripts/check-dist.mjs / scripts/build-catalog.mjs — /apps gets its own prerendered SEO head, sitemap entry, llms.txt entry, and dist audit.
• terraform/cloudfront-function.js — rewrites /apps → /apps/index.html (same pattern as /app/<slug>).
• public/site.webmanifest — Apps PWA shortcut.
• src/i18n/messages/*.ts (all 14 locales) — new copy for the tabs + Apps page.
• SPEC.md / README.md — document the new route + presentation.
• tests/a11y/apps.spec.ts — new Playwright a11y/interaction suite (axe WCAG 2.2 AA, keyboard operability, tab switching, dark+light theme).

Test plan

• npm run lint — 0 errors (4 pre-existing unrelated warnings)
• npx tsc --noEmit — clean
• npm run test:coverage — 190/190 unit tests pass, 99.65% line coverage
• npm run build — clean build + prerender + check-dist audit passes
• npm run test:a11y (Playwright, desktop + mobile projects) — 60/60 pass, axe-clean on /apps in dark AND light theme, keyboard operability verified
• Manually screenshotted /apps at mobile 390 and desktop 1280 — phone-home-screen read confirmed at mobile width, graceful desktop scale-up, no overflow, comfortable tap targets, consistent section spacing

Version bump

0.2.0 → 0.3.0 (minor) — new user-facing capability (feat:), fully backwards compatible with the existing store/detail views and catalog format.