Regenerate agent instructions from state-hub templates (CUST-WP-0055 T01)

Sync AGENTS.md, CLAUDE.md, and .claude/rules from updated project_rules
templates: workplan-first session protocol, legacy terminology footnote,
and GET /workplans/ examples.

.claude/rules/workplan-convention.md

@@ -24,7 +24,7 @@ multiple planned phases into a normal workplan.
 Ecosystem todos from other agents arrive as `[repo:railiance-platform]` hub tasks —
 visible at session start. Pick one up by creating the workplan file, committing,
 and running `statehub fix-consistency` — C-06 registers the workplan in the hub.
-Never register by hand with `create_workplan`/`create_workstream`.
+Never register by hand with `create_workplan` (legacy MCP alias: `create_workstream`).
 
 Task blocks use this shape:
 
@@ -39,7 +39,17 @@ Status progression is `todo` → `progress` → `done`; use `wait` for waiting o
 blocked work and `cancel` for stopped work.
 
 Workplan frontmatter carries `state_hub_workstream_id` — a legacy field name
-kept for compatibility ("workstream" is the old term for workplan); it holds
-the hub workplan id and is written by fix-consistency. Do not edit or rename it.
+kept for compatibility; it holds the hub workplan UUID and is written by
+fix-consistency. Do not edit or rename it.
+
+### Legacy terminology (compatibility footnote)
+
+**Workplan** is the fleet term — see
+`the-custodian/canon/standards/workplan-terminology-fleet_v0.1.md`.
+**Workstream** is legacy only: some API routes (`/workstreams/`), params
+(`workstream_id`), MCP aliases (`create_workstream`), and the frontmatter field
+above remain until `STATE-WP-0069` retires them via legacy-meter. Treat those
+identifiers as workplan IDs. Prefer `GET /workplans/` and `workplan_id` in new
+examples and scripts.
 
 <!-- Ralph Loop rules and HEUREKA sequence: ~/.claude/CLAUDE.md — do not duplicate here -->