BAZ-017: Complete production harness editors and migration

[rullopat]

Summary

• add canonical server-backed Team and Group Flow/Matrix editors with conflict and source recovery
• add exact lifecycle previews, reviewed BAZ-009 migration, durable block details, and chat return state
• complete responsive/accessibility QA and activate management contract version 1

Verification

• pnpm test (92 files, 718 tests)
• pnpm typecheck
• pnpm --filter @bazilion/web typecheck
• pnpm lint (existing warnings only)
• pnpm build
• pnpm --filter @bazilion/web build
• focused activation/editor/API suite (5 files, 26 tests)
• git diff --check
• in-app Browser QA at 1440x900, 1024x768, and 390x844 in light/dark; no real Agent messages sent