Precompute dashboard metrics and tune production workload

[McanKul]

Summary

• Add persistent PostgreSQL snapshots for query metrics and global/database trends, plus a background refresh worker.
• Serve dashboard windows from precomputed data and keep bounded cache/fallback behavior.
• Add production Caddy/Compose bootstrap files and variable workload pacing.
• Harden source-registration shell quoting and make fresh-stack validation wait for/refresh the snapshots its fixtures consume.
• Bump the product to 1.1.1 with repository migration 0016 and update migration/rollback documentation.

Validation

• GitHub CI: repository contracts, backend, frontend, and fresh PostgreSQL stack all passed.
• Backend: 243 tests passed.
• Frontend: 66 tests passed; production build passed.
• Deployment components: join snapshotter 17, workload 31, role reconciler 9, ERP benchmark 64 tests passed.
• Migration runner/manifest: 6 tests passed; release consistency passed.
• PostgreSQL 18 migration smoke: migrations 0015/0016, first population, and concurrent refresh passed for metric and trend snapshots.
• Fresh-stack integration: clean volumes, health/readiness, migration idempotency, persisted 0013→0016 upgrade, role drift repair, full verifier, 30d replay snapshot, disposable clone runtime/policy, and cleanup passed.
• Production: all 10 services are running; API/repository/collector are healthy; application 1.1.1 and repository 0016/16 are current.
• The live large-data verifier's final data-dependent candidate scan found no currently beneficial single-column index and correctly returned NO_IMPROVEMENT; persisted HypoPG validation passed and no unsafe DDL or false recommendation was produced.