docs: close WP-0005 workplan and bind State Hub tasks

Add frontmatter tasks list with state_hub_task_id links, completion
section for v1.2.0 ship, and custodian brief from hub sync.

.custodian-brief.md

@@ -0,0 +1,18 @@
+<!-- custodian-brief: generated by fix-consistency — do not edit manually -->
+# Custodian Brief — kaizen-agentic
+
+**Domain:** custodian
+**Last synced:** 2026-06-16 23:01 UTC
+**State Hub:** http://127.0.0.1:8000 *(adjust if running on a remote machine)*
+
+## Active Workstreams
+
+*(none — repo may need first-session setup)*
+
+---
+## MCP Orientation (when available)
+
+If the state-hub MCP server is reachable, call:
+`get_domain_summary("custodian")`
+This provides richer cross-domain context.
+If the MCP call fails, use this file as your orientation source.