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/define-call-graph-retention.md

@@ -0,0 +1,37 @@
+---
+id: define-call-graph-retention
+name: Define Call Graph Retention Policy
+status: completed
+depends_on: []
+scope: narrow
+risk: low
+impact: component
+level: implementation
+---
+
+## Description
+
+W09: Call graph data grows unboundedly — every operation invocation creates a node and edges. CASCADE handles cleanup on node deletion, but nothing deletes old nodes. README.md acknowledges this as Open Question #5 but no approach is specified.
+
+Specify the intended approach: TTL-based deletion, archival to cold storage, or aggregation + deletion. Even a phased notation ("v1: manual cleanup, v2: automatic TTL") helps implementers understand the plan.
+
+## Acceptance Criteria
+
+- [ ] `call-graph.md` includes a "Retention Policy" section
+- [ ] Short-term approach specified (e.g., manual cleanup or no cleanup for v1)
+- [ ] Long-term approach outlined (e.g., TTL-based, aggregation + deletion)
+- [ ] README.md Open Question #5 resolved with cross-reference to call-graph.md section
+
+## References
+
+- docs/reviews/storage-architecture-review-2026-04-21.md#W09
+- docs/architecture/storage/call-graph.md
+- docs/architecture/storage/README.md (Open Question #5)
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion