docs(roadmap): insert phase 11.2 ready-to-share website and newsletter plugin

Adds Phase 11.2 after 11.1: the sm-summercms-app root with a
vue-summercms-app website, an sm-newsletter-plugin stub ported from
Golem15.Newsletter with double opt-in signup, and the 11.1 docs served
at /docs. Records the sm- repo naming convention.

.planning/STATE.md

@@ -5,12 +5,12 @@ current_phase: "10.1"
 current_phase_name: Runtime admin extension point
 status: executing
 stopped_at: Completed 10.1-01-PLAN.md
-last_updated: "2026-09-28T21:54:19.404Z"
+last_updated: "2026-09-29T00:03:16.308Z"
 last_activity: 2026-09-28
 last_activity_desc: Phase 10.1 execution started
-state_head: 2325d80ecb5d93e093a4388e45dd53a96fbea9d1
+state_head: c3b76b1afb977cb3f72272f9876c65c8da7877ed
 progress:
-  total_phases: 18
+  total_phases: 19
   completed_phases: 9
   total_plans: 78
   completed_plans: 75
@@ -139,6 +139,7 @@ Progress: [██████░░░░] 60%
 - Phase 10.1 inserted after Phase 10: Runtime admin extension point (URGENT)
 - Phase 10.2 inserted after Phase 10: Nest framework packages under modules and write run docs (URGENT)
 - Phase 11.1 inserted after Phase 11: SummerCMS documentation for humans and AI agents, modelled on wintercms.com/docs; after core framework, before Płytarium API port
+- Phase 11.2 inserted after Phase 11.1: Ready to share: summercms.io website (sm-summercms-app + vue-summercms-app), sm-newsletter-plugin stub with double opt-in, 11.1 docs at /docs
 
 ### Decisions