docs: update workspace + common-plat inventory with accurate scan data
- Package count: 53 → 58 (added backend-config, backend-flags,
backend-telemetry, fastify-auth, field-encrypt)
- New §2.6 Security section for @bytelyst/field-encrypt
- Product table: added Encrypted column (5 backends using field-encrypt)
- Test summary: replaced vague estimates with actual file counts (538 total)
- LocalMemGPT: fixed stack from 'React, Express' → 'Fastify 5, Next.js 16,
SQLite, Ollama' and added to product table (port 4019)
- Architecture diagram: 9→10 products, 53→58 packages, added LocalMemGPT
- Updated notes about SmartAuth (docs-only), temp_uxlab (empty)
- Bumped last-updated dates to 2026-03-21