feat: strengthen water and foreground silhouettes

- Upgrade river shader with multi-layer UV flow, fresnel edges, foam highlights, and specular sparkle
- Upgrade waterfall shader with dual-band scrolling, distinct foam contrast, and rim transparency
- Widen river (8m) and waterfall (8m) for greater visual presence
- Increase waterfall mist particles to 72 with wider spread and longer lifetime
- Add fortress crenellations (10), three turrets, and prominent ridge banner for readable skyline silhouette
- Remove duplicate banner nodes from JajceWorld instance (now owned by FortressBlockout scene)
- Update BUILD_IN_PUBLIC_PLAN and LEARNING_ROADMAP to reflect completion

docs/BUILD_IN_PUBLIC_PLAN.md

@@ -644,10 +644,21 @@ Completed:
     study desk, and rest bench now have compact presentation props that remain
     readable in the runtime cinematic frame.
 
+Completed:
+
+15. Water and foreground silhouette strengthening: river/waterfall shaders
+    now include multi-layer UV flow, fresnel edges, foam highlights, sparkle
+    specular, and better color depth; the waterfall has distinct foam bands
+    and rim transparency; mist particle count and spread increased; the river
+    and waterfall widened; the fortress ridge landmark now has crenellations,
+    a dedicated banner pole with larger banner, and three turrets for a more
+    readable silhouette against the sky.
+
 Next:
 
-1. Strengthen water and foreground silhouettes without adding new simulation
-   mechanics.
+1. Continue growing resource discovery with finite ResourceNode instances
+   placed in meaningful contexts (from LEARNING_ROADMAP). See the roadmap
+   for the next systems priority.
 
 Do not start with GIS data, a full city, a large asset pack, or more NPC
 mechanics. The next proof is a beautiful stage for the systems that already