Fix stale closures in useCallback with empty dependency arrays

[tmshv]

Problem

Several components use useCallback with empty or incomplete dependency arrays, causing stale closures where the callback captures outdated state/props.

Affected files

1. src/components/LayersOutline/index.tsx:55, 86 — moveLayerItem and renderLayerItem callbacks have empty [] dependency arrays but use values that can change
2. src/components/SourcesOutline/index.tsx:28-57 — same pattern
3. src/components/LeftSidebar/LayersTab.tsx:29 — onClick callback with empty dependency array

What needs to change

Add the correct dependencies to each useCallback array. Consider enabling the react-hooks/exhaustive-deps ESLint rule (see related issue) to catch these automatically.