feat: add rain puddles and stabilize shoreline water

docs/ATTRIBUTION.md

@@ -309,9 +309,9 @@ revision-specific inventory.
 
 ## Generated resources
 
-Godot `.import` sidecars and deterministic shoreline `.tres` meshes are derived
-repository resources, not original artwork. `.godot/imported/`, editor caches,
-captures, exports, and temporary test data are not tracked.
+Godot `.import` sidecars and other deterministic generated resources are
+derived repository resources, not original artwork. `.godot/imported/`, editor
+caches, captures, exports, and temporary test data are not tracked.
 
 ## Release gate
 

docs/DEVELOPMENT.md

@@ -233,12 +233,10 @@ materials local to the scene.
 
 ### Shoreline presentation
 
-The visible shoreline treatment is currently produced by the water materials.
-The older smooth-ribbon baker and generated starter-island ribbon resource are
-retained as development history/tooling, but the ribbon mesh is disabled and
-is not part of the current rendered shoreline. Do not treat a ribbon rebuild
-as a normal terrain-authoring requirement or re-enable the mesh as incidental
-cleanup.
+The visible shoreline treatment is produced entirely by the water materials.
+It does not require supplemental shoreline meshes or generation tooling. Keep
+shoreline foam and edge-effect work in the water materials rather than adding
+terrain-authoring requirements.
 
 ### Facial-feature textures
 

docs/PORTMASTER.md

@@ -235,7 +235,7 @@ profile also:
 - keeps the title water and full-window menu patterns static;
 - replaces the animated cooler water and decorative bubbles with flat water;
 - disables decorative title-screen fish and bubbles;
-- retains title and dusk music while omitting rain and shoreline ambience;
+- retains title and dusk music while omitting rain ambience;
 - reduces rain to 48 particles simulated at 8 FPS; and
 - replaces procedural sky clouds and 81 moving local cloud patches with one
   flat cloud ceiling.