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-session-version-semantics.md

@@ -0,0 +1,38 @@
+---
+id: define-session-version-semantics
+name: Define sessions.version Semantics and Default
+status: completed
+depends_on: []
+scope: narrow
+risk: medium
+impact: component
+level: implementation
+---
+
+## Description
+
+W10: The `sessions.version` column is `text NOT NULL` described as "Schema version (opencode compat)" but no valid values, default, or versioning scheme is defined. README.md Open Question #1 on versioning `data` columns is unresolved.
+
+Define the initial version value (e.g., `"1"`), document what `version` governs (the `data` JSONB shape? the message/parts schema? opencode compatibility only?), and specify the default for hub-direct sessions vs opencode imports.
+
+## Acceptance Criteria
+
+- [ ] Valid version values defined (e.g., `"1"`, with convention for future updates)
+- [ ] Documented what `version` governs (data schema, session schema, or opencode compat only)
+- [ ] Default value for hub-direct sessions specified
+- [ ] Default value for opencode-imported sessions specified
+- [ ] `sessions.md` updated with the versioning contract
+
+## References
+
+- docs/reviews/storage-architecture-review-2026-04-21.md#W10
+- docs/architecture/storage/sessions.md:24
+- docs/architecture/storage/README.md (Open Question #1)
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion