rename(phase 1): CapaKraken → Nexus across code, UI, docs, CI

- @capakraken/* → @nexus/* across 12 packages (root + 11 workspaces),
  1551 import lines migrated via codemod
- User-visible brand strings renamed (emails, page titles, PWA
  manifest, mobile header, MFA backup-codes header, tooltips, signin
  page, invite page, weekly digest, install prompt)
- TOTP issuer "CapaKraken" → "Nexus" (existing secrets still valid;
  re-enrollment relabels them in users' authenticator apps)
- Function rename: assertCapaKrakenDbTarget → assertNexusDbTarget
- LocalStorage migration shim in apps/web/src/app/layout.tsx copies
  capakraken_* → nexus_* on first load (guarded by nexus_migrated_v1
  sentinel; runs once per browser, then never again)
- Service-worker cache name capakraken-v2 → nexus-v2 with one-time
  caches.delete('capakraken-v2') from the same shim
- Email-domain fixtures @capakraken.{dev,app} → @nexus.{dev,app} in
  seed data, e2e specs, SMTP default fallback
- Dockerfile.dev / Dockerfile.prod / all .github/workflows/*.yml
  pnpm --filter @capakraken/* → @nexus/*
- README, CLAUDE.md, LEARNINGS.md, all docs/*.md, .env.example,
  tooling/deploy/.env.production.example brand sweep

Phase 1 deliberately leaves untouched (handled in Phase 3 cutover):
- PostgreSQL DB name "capakraken" and POSTGRES_USER "capakraken"
- Volume names capakraken_pgdata etc.
- Compose project name "capakraken" / "capakraken-prod"
- db-target-guard default expectedDatabase
- env-var CAPAKRAKEN_EXPECTED_DB_NAME
- Container DNS names in docker-compose.ci.yml

Quality gates green: pnpm typecheck (7/7), pnpm test:unit (7/7),
pnpm lint (0 errors), check:exports/imports/architecture all pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/web/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "@capakraken/web",
+  "name": "@nexus/web",
   "version": "0.1.0",
   "private": true,
   "scripts": {
@@ -13,11 +13,11 @@
     "test:e2e:email": "playwright test --config playwright.dev.config.ts e2e/dev-system/invite-flow.spec.ts e2e/dev-system/password-reset.spec.ts"
   },
   "dependencies": {
-    "@capakraken/api": "workspace:*",
-    "@capakraken/application": "workspace:*",
-    "@capakraken/db": "workspace:*",
-    "@capakraken/engine": "workspace:*",
-    "@capakraken/shared": "workspace:*",
+    "@nexus/api": "workspace:*",
+    "@nexus/application": "workspace:*",
+    "@nexus/db": "workspace:*",
+    "@nexus/engine": "workspace:*",
+    "@nexus/shared": "workspace:*",
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
     "@dnd-kit/utilities": "^3.2.2",
@@ -51,8 +51,8 @@
   "devDependencies": {
     "@next/bundle-analyzer": "^16.2.3",
     "@axe-core/playwright": "^4.11.1",
-    "@capakraken/eslint-config": "workspace:*",
-    "@capakraken/tsconfig": "workspace:*",
+    "@nexus/eslint-config": "workspace:*",
+    "@nexus/tsconfig": "workspace:*",
     "@playwright/test": "^1.49.1",
     "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.2",