Task: Implement the Desktop Entry Locator feature

TASK-DESCRIPTION

• Create sources/desktop/desktop_entry_locator.h.
• Create sources/desktop/desktop_entry_locator.cpp.
• Create the portable test tests/20-desktop-entry-locator.sh.
• Create the live-state test tests/50-desktop-search-path-live.sh.
• Implement the requirements in prompts/features/05-desktop-entry-locator.md.
• Run make test from the repository root.

TASK-OUTPUT

• Report the created files and the result of make test.

TASK-CONTEXT

• Feature requirements: prompts/features/05-desktop-entry-locator.md.
• Search-path facts and observed host values: documents/09-desktop-file-search-paths.md.
• The locator reads XDG_DATA_HOME, XDG_DATA_DIRS, XDG_CONFIG_HOME, XDG_CONFIG_DIRS, and HOME.
• The live-state test declares its prerequisites in its header and reports PASS/WARN/FAIL.

TASK-FILES

• sources/desktop/desktop_entry_locator.h — new
• sources/desktop/desktop_entry_locator.cpp — new
• tests/20-desktop-entry-locator.sh — new
• tests/50-desktop-search-path-live.sh — new