chore: remove unused panel icon resources

Remove panel-left-symbolic.svg and panel-right-symbolic.svg
as they are no longer needed.

docs/features.md

@@ -199,10 +199,3 @@ Full keyboard-driven workflow:
 - **Planned**: Design complete, implementation pending
 - **Partial**: Basic functionality exists, enhancements needed
 - **In Progress**: Currently being developed
-
-## Contributing
-
-Features marked as "Planned" have their message handlers already prepared in the codebase. Look for:
-- `OpenPath`, `RefreshMetadata` in `src/app/message.rs`
-- `ToggleCropMode`, `ToggleScaleMode` in transformation handlers
-- Comments marked with `TODO:` in document implementations

resources/icons/hicolor/scalable/actions/panel-left-symbolic.svg

@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg width="16" height="16" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg">
-  <rect x="1" y="2" width="14" height="12" rx="1" ry="1" fill="none" stroke="currentColor" stroke-width="1.5"/>
-  <line x1="5" y1="2" x2="5" y2="14" stroke="currentColor" stroke-width="1.5"/>
-</svg>

resources/icons/hicolor/scalable/actions/panel-right-symbolic.svg

@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg width="16" height="16" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg">
-  <rect x="1" y="2" width="14" height="12" rx="1" ry="1" fill="none" stroke="currentColor" stroke-width="1.5"/>
-  <line x1="11" y1="2" x2="11" y2="14" stroke="currentColor" stroke-width="1.5"/>
-</svg>