refactor(plan): remove generic mode abstraction

scripts/gen-doc-graphs.ts

@@ -70,7 +70,7 @@ const GROUP_ORDER = [
   'web',
   'spill',
   'todo',
-  'mode',
+  'plan',
   'cordis',
   'hooks',
   'session-persistence',
@@ -172,12 +172,12 @@ const SERVICE_ROLES: ServiceRole[] = [
     note: 'UI front doors provide the active human-answer provider; tool-ask-user pauses a tool call on the provider-neutral ask() promise.',
   },
   {
-    key: 'modes',
-    pkg: 'mode',
-    title: 'Session-mode state',
+    key: 'planMode',
+    pkg: 'plan-mode',
+    title: 'Plan collaboration state',
     mode: 'core',
     consumers: ['acp'],
-    note: 'Folds logged per-agent mode/set state, flushes user flips at turn boundaries, renders deployment-owned guidance, and keeps the plan-exit schema stable across modes.',
+    note: 'Folds logged plan/mode state, flushes user selections at turn boundaries, renders deployment-owned guidance, registers /plan, and keeps the plan-exit schema stable across transitions.',
   },
   {
     key: 'commands',