Setup repo: migrate architecture specs, code stubs, and tasks from alkhub_ts

Copy architecture docs, ADRs, storage domain specs, research, reviews,
and 56 storage architecture tasks from the alkhub_ts monorepo. Adapt for
standalone @alkdev/hub repo structure (src/ not packages/hub/).

Sanitize all sensitive information:
- Replace private IPs (10.0.0.1) with localhost defaults
- Remove internal server hostnames (dev1, ns528096)
- Replace /workspace/ private paths with npm package references
- Remove hardcoded credentials from examples
- Rewrite infrastructure.md without private network details

Add Deno project scaffolding: deno.json (pinned deps), .gitignore,
AGENTS.md, entry point. Migrate existing code stubs (crypto, config
types, logger) with updated import paths.

tasks/architecture/storage/cascade-decisions.md

@@ -0,0 +1,32 @@
+---
+id: cascade-decisions
+name: Cascade Decisions
+status: completed
+depends_on: [resolve-sessions-accountid-cascade, resolve-audit-logs-ownerid-cascade, split-operations-into-definitions-and-registrations, add-call-graph-edges-indexes-cascades, add-missing-cascade-entries]
+scope: moderate
+risk: critical
+impact: phase
+level: review
+---
+
+## Description
+
+All FK cascade resolution tasks. This group consolidates every decision about ON DELETE/ON UPDATE behavior for foreign keys across the storage layer. Getting these wrong causes data loss or orphaned rows, so all cascade policies must be resolved and documented before any implementation begins.
+
+## Acceptance Criteria
+
+- [ ] All dependent tasks are completed
+- [ ] Cross-references between completed tasks are consistent
+- [ ] No remaining contradictions in the covered domain
+
+## References
+
+- docs/reviews/storage-architecture-review-2026-04-21.md
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion