fix: WebView icon cache + Interface↔Interface block + G network save panic

## Fixes
- Renamed palette icons to bust WebView cache (interface-icon.png, subsystem-icon.png)
- Block Interface↔Interface connections with user warning (deferred feature)
- Fix save panic for G network flows: FlowStartConnection/FlowEndConnection
  targets now correctly point to parent system when source/dest is interface

## Root Causes
- WebView was caching bad responses for original icon filenames
- Save system expects flow targets to be systems, not interfaces directly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: rsthornton

assets/palette-icons/interface.png assets/palette-icons/interface-icon.pngassets/palette-icons/interface.png renamed to assets/palette-icons/interface-icon.png

@@ -242,6 +242,12 @@ pub fn finalize_connection(
         let dest_is_interface = interface_query.get(destination_entity).is_ok();
         let dest_is_external = external_entity_query.get(destination_entity).is_ok();
 
+        // Block Interface ↔ Interface connections (deferred - direction logic not stable)
+        if source_is_interface && dest_is_interface {
+            warn!("❌ Interface ↔ Interface connections coming in future version");
+            continue;
+        }
+
         // Phase 3A: Check if entities have InterfaceBehavior (subsystem-capable interfaces)
         let source_has_interface_behavior = interface_behavior_query.get(source_entity).is_ok();
         let dest_has_interface_behavior = interface_behavior_query.get(destination_entity).is_ok();
@@ -311,7 +317,11 @@ pub fn finalize_connection(
             subsystem_query.get(source_entity).unwrap().0.parent_system
         } else if dest_is_subsystem {
             // Dest is a subsystem - parent flow to its parent_system
-            subsystem_query.get(destination_entity).unwrap().0.parent_system
+            subsystem_query
+                .get(destination_entity)
+                .unwrap()
+                .0
+                .parent_system
         } else if source_is_interface {
             // Interface's parent might be a subsystem - check and get grandparent
             let interface_parent = parent_query
@@ -483,16 +493,38 @@ pub fn finalize_connection(
             EndTargetType::System
         };
 
+        // Determine the actual targets for FlowStartConnection/FlowEndConnection
+        // For interfaces: target should be the interface's parent SYSTEM, not the interface itself
+        // This matches how the save system expects flows to be structured
+        let start_target = if source_is_interface {
+            // Get the interface's parent (the system it's attached to)
+            parent_query
+                .get(source_entity)
+                .map(|p| p.get())
+                .expect("Interface should have parent")
+        } else {
+            source_entity
+        };
+
+        let end_target = if dest_is_interface {
+            parent_query
+                .get(destination_entity)
+                .map(|p| p.get())
+                .expect("Interface should have parent")
+        } else {
+            destination_entity
+        };
+
         // Add connection components to link flow to source and destination
         let mut flow_commands = commands.entity(flow_entity);
 
         flow_commands.insert((
             FlowStartConnection {
-                target: source_entity,
+                target: start_target,
                 target_type: start_target_type,
             },
             FlowEndConnection {
-                target: destination_entity,
+                target: end_target,
                 target_type: end_target_type,
             },
         ));
@@ -570,7 +602,12 @@ fn compute_endpoint_for_entity_world(
 
         if let (Some(other_pos), Some(other_dir)) = (other_end, other_end_dir) {
             // Use zoomed radius (system.radius * scale)
-            compute_end_and_direction_from_subsystem(pos, system.radius * scale, other_pos, other_dir)
+            compute_end_and_direction_from_subsystem(
+                pos,
+                system.radius * scale,
+                other_pos,
+                other_dir,
+            )
         } else {
             // First pass - use a placeholder direction (will be recomputed)
             (pos, Vec2::X)

assets/palette-icons/subsystem.png assets/palette-icons/subsystem-icon.pngassets/palette-icons/subsystem.png renamed to assets/palette-icons/subsystem-icon.png

@@ -51,8 +51,8 @@ const PALETTE_ICON_SIZE: f32 = 40.0;
 /// Maps PaletteElementType to its icon asset path.
 fn icon_path_for(element_type: PaletteElementType) -> &'static str {
     match element_type {
-        PaletteElementType::Subsystem => "palette-icons/subsystem.png",
-        PaletteElementType::Interface => "palette-icons/interface.png",
+        PaletteElementType::Subsystem => "palette-icons/subsystem-icon.png",
+        PaletteElementType::Interface => "palette-icons/interface-icon.png",
         PaletteElementType::EnvironmentalObject => "palette-icons/source.png", // Reuse source icon for now
     }
 }
@@ -193,7 +193,10 @@ pub fn handle_leptos_palette_click(
             .id();
 
         placement_mode.ghost_entity = Some(ghost);
-        info!("✨ Entered placement mode for {:?} (from Leptos)", element_type);
+        info!(
+            "✨ Entered placement mode for {:?} (from Leptos)",
+            element_type
+        );
     }
 }
 

src/bevy_app/systems/connection_mode.rs

@@ -18,12 +18,12 @@ pub fn Palette(
         <div class="fixed left-0 top-20 bottom-0 w-16 bg-stone-50 shadow-md z-10 flex flex-col items-center py-3 space-y-2">
             <PaletteButton
                 element_type=PaletteElementTypeEvent::Subsystem
-                icon_path="assets/palette-icons/subsystem.png"
+                icon_path="assets/palette-icons/subsystem-icon.png"
                 on_click=on_element_click
             />
             <PaletteButton
                 element_type=PaletteElementTypeEvent::Interface
-                icon_path="assets/palette-icons/interface.png"
+                icon_path="assets/palette-icons/interface-icon.png"
                 on_click=on_element_click
             />
             <PaletteButton