rename(phase 3): compose/DB/infra names + stray code refs capakraken → nexus

- docker-compose.yml / .prod.yml / .ci.yml: project names, POSTGRES_DB/USER,
  pg_isready, DATABASE_URL, volume names (nexus_pgdata, nexus_prod_*)
- .github/workflows/ci.yml: POSTGRES_PASSWORD, pg_isready, psql credentials,
  GRANT statements, POSTGRES_PASSWORD=nexus_dev for Docker Deploy job
- scripts/db-target-guard.mjs: expectedDatabase default, NEXUS_EXPECTED_DB_NAME
- scripts/prisma-with-env.mjs, e2e/test-server.mjs: env-var rename
- packages/db/src/safe-destructive-env.ts + reset-dispo-import.ts: DB name set
- packages/db/src/destructive-db-guard.ts: PROTECTED_DATABASE_NAMES → "nexus"
- packages/db/src/destructive-db-guard.test.ts: all fixture DB names + comments
- .env.example, tooling/deploy/deploy.env.example: DATABASE_URL, image refs
- packages/api: Redis channel/key prefixes (rbac-invalidate, sse, ratelimit),
  logger service name, app-base-url log prefix
- E2E: DB container names, localStorage/sessionStorage keys, email domains
- scripts: architecture-guardrails filter, export/import-dev-seed defaults,
  harden-postgres defaults, start.sh pg_isready, worktree-hygiene fixture
- tooling/migrate/rename-to-nexus.sh: new maintenance-window cutover script

Only intentional capakraken survivor: anonymization.ts DEFAULT_ANONYMIZATION_SEED
(functional cryptographic constant — changing it would invalidate stored aliases).

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

docker-compose.prod.yml

@@ -1,4 +1,4 @@
-name: capakraken-prod
+name: nexus-prod
 
 services:
   postgres:
@@ -7,8 +7,8 @@ services:
     ports:
       - "127.0.0.1:${POSTGRES_PORT:-5432}:5432"
     environment:
-      POSTGRES_DB: capakraken
-      POSTGRES_USER: capakraken
+      POSTGRES_DB: nexus
+      POSTGRES_USER: nexus
       POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD}
     command: >
       postgres
@@ -18,9 +18,9 @@ services:
       -c log_line_prefix='%t [%p] %u@%d '
       -c log_min_duration_statement=1000
     volumes:
-      - capakraken_prod_pgdata:/var/lib/postgresql/data
+      - nexus_prod_pgdata:/var/lib/postgresql/data
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U capakraken -d capakraken"]
+      test: ["CMD-SHELL", "pg_isready -U nexus -d nexus"]
       interval: 10s
       timeout: 5s
       retries: 5
@@ -34,7 +34,7 @@ services:
       - "127.0.0.1:${REDIS_PORT:-6379}:6379"
     command: redis-server --maxmemory 256mb --maxmemory-policy allkeys-lru --requirepass ${REDIS_PASSWORD}
     volumes:
-      - capakraken_prod_redis:/data
+      - nexus_prod_redis:/data
     healthcheck:
       test: ["CMD", "redis-cli", "-a", "${REDIS_PASSWORD}", "--no-auth-warning", "ping"]
       interval: 10s
@@ -49,7 +49,7 @@ services:
     env_file:
       - .env.production
     environment:
-      DATABASE_URL: postgresql://capakraken:${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD}@postgres:5432/capakraken
+      DATABASE_URL: postgresql://nexus:${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD}@postgres:5432/nexus
       REDIS_URL: redis://:${REDIS_PASSWORD}@redis:6379
       RATE_LIMIT_BACKEND: ${RATE_LIMIT_BACKEND:-redis}
     depends_on:
@@ -67,7 +67,7 @@ services:
     env_file:
       - .env.production
     environment:
-      DATABASE_URL: postgresql://capakraken:${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD}@postgres:5432/capakraken
+      DATABASE_URL: postgresql://nexus:${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD}@postgres:5432/nexus
       REDIS_URL: redis://:${REDIS_PASSWORD}@redis:6379
       RATE_LIMIT_BACKEND: ${RATE_LIMIT_BACKEND:-redis}
       NEXT_PUBLIC_SENTRY_DSN: ${NEXT_PUBLIC_SENTRY_DSN:-}
@@ -84,7 +84,7 @@ services:
       start_period: 30s
 
 volumes:
-  capakraken_prod_pgdata:
-    name: capakraken_prod_pgdata
-  capakraken_prod_redis:
-    name: capakraken_prod_redis
+  nexus_prod_pgdata:
+    name: nexus_prod_pgdata
+  nexus_prod_redis:
+    name: nexus_prod_redis