remove the remainder of PWA functionality that wasn't being used, and fix the web "share target"

.cursor/rules/architecture/build_validation.mdc

@@ -35,7 +35,7 @@
 
 - **Development**: `npm run dev` - serve and load app
 
-- **Production**: `npm run build:web:prod` - verify SW and WASM present
+- **Production**: `npm run build:web:prod` - verify WASM present
 
 ### Mobile Platforms
 
@@ -98,13 +98,11 @@
   verify single-instance,
   icons, signing
 
-### Service Worker / WASM
+### WASM
 
-- **Trigger**: `sw_combine.js`, WASM copy path
+- **Trigger**: WASM copy path
 
-- **Validation**: Verify combined SW exists and is injected; page loads offline;
-
-  WASM present
+- **Validation**: WASM present
 
 ### Docker