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/improve-mappings-spec.md

@@ -0,0 +1,38 @@
+---
+id: improve-mappings-spec
+name: Improve Mappings Spec — Project Scoping and Status Lifecycle
+status: completed
+depends_on: []
+scope: narrow
+risk: trivial
+impact: isolated
+level: implementation
+---
+
+## Description
+
+Two improvements to the `mappings` table specification in `coordination.md`:
+
+1. **S13**: Finding all active mappings for a project's tasks requires a JOIN through `sessions.projectId` or `tasks.projectId`. Either add a denormalized `projectId` column for direct project-scoped queries, or document that the JOIN pattern is acceptable and intentional.
+
+2. **S14**: Unlike `tasks.status` which has an explicit lifecycle diagram, `mappings.status` transitions are unspecified. Add a lifecycle diagram or state machine showing valid transitions (e.g., `active → completed | failed | aborted`).
+
+## Acceptance Criteria
+
+- [ ] Either `projectId` column added to mappings table spec, or JOIN pattern documented as intentional
+- [ ] `mappings.status` lifecycle diagram added to `coordination.md` with valid transitions
+- [ ] `table-reference.md` updated if schema changes
+
+## References
+
+- docs/reviews/storage-architecture-review-2026-04-21.md#S13
+- docs/reviews/storage-architecture-review-2026-04-21.md#S14
+- docs/architecture/storage/coordination.md
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion