The content-aware-resize tool had a full backend implementation (API route,
caire binary, seam-carving bridge) but was missing from the frontend
toolRegistry Map. Navigating to /content-aware-resize showed "Tool not found"
because ToolPage could not resolve a registry entry for the tool ID.
Added a dedicated ContentAwareResizeSettings component and registered it in
the tool registry with side-by-side display mode. Also added a guard test
that verifies every tool in the shared TOOLS[] array has a matching registry
entry, preventing this class of bug from recurring.
Closes#131
Closes the last coverage gap from the master test matrix - 11 tests
covering toggle behavior, control visibility, input validation,
square mode, slider ranges, and end-to-end processing for PNG/HEIC.
SnapOtter