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/add-missing-indexes-sessions.md

@@ -0,0 +1,42 @@
+---
+id: add-missing-indexes-sessions
+name: Add Missing Indexes — Sessions & Coordination Domain
+status: completed
+depends_on: []
+scope: narrow
+risk: low
+impact: component
+level: implementation
+---
+
+## Description
+
+W03 (partial): Add missing indexes for sessions and coordination domain tables.
+
+Missing indexes:
+- `sessions`: `unq_sessions_slug` — UNIQUE constraint on `slug` not listed (unlike other UNIQUEs)
+- `sessions`: `idx_sessions_parent_id` on `(parentId)` — find child sessions of coordinator
+- `detections`: `idx_detections_session_id` on `(sessionId)` — find detections for a session (table currently has no indexes at all)
+- `mappings`: `idx_mappings_workspace_id` on `(workspaceId)` — workspace-scoped mapping queries
+
+## Acceptance Criteria
+
+- [ ] `table-reference.md` indexes section includes `unq_sessions_slug`, `idx_sessions_parent_id`, `idx_detections_session_id`, `idx_mappings_workspace_id`
+- [ ] Per-domain docs (`sessions.md`, `coordination.md`) reference the new indexes
+- [ ] `detections` table now has at least one index documented
+- [ ] All new indexes have documented purpose (query pattern)
+
+## References
+
+- docs/reviews/storage-architecture-review-2026-04-21.md#W03
+- docs/architecture/storage/table-reference.md:87-145
+- docs/architecture/storage/sessions.md
+- docs/architecture/storage/coordination.md
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion