Namespace the coverage target when embedded

Follows a87cbfb: a sibling dependency may ship a `coverage` target of its
own, so a non-top-level build gets `akstdlib_coverage` instead. The
top-level name is unchanged, and so is every documented command.

Verified: cmake --build build-coverage --target coverage still runs the
suite (14/14) and reports 99.0% of lines; the mutation target still
resolves.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CMakeLists.txt

@@ -274,6 +274,14 @@ if(AKSL_COVERAGE AND Python3_FOUND)
   # 30s the test binaries get.
   set_tests_properties(coverage_reset coverage_report PROPERTIES TIMEOUT 300)
 
+  # Namespaced when embedded in another project, for the same reason the mutation
+  # target below is: a sibling dependency may well ship a `coverage` target too.
+  if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+    set(AKSL_COVERAGE_TARGET coverage)
+  else()
+    set(AKSL_COVERAGE_TARGET akstdlib_coverage)
+  endif()
+
   # Convenience entry point that also builds the test binaries first. It runs
   # the suite rather than the script directly, because the two fixture tests
   # above already reset the counters and produce the report -- and CTest pulls a
@@ -281,14 +289,14 @@ if(AKSL_COVERAGE AND Python3_FOUND)
   # run the tests without them. The second command re-reads the same counters to
   # print the report that CTest suppressed for the passing coverage_report test
   # (it only spawns gcov again, it does not re-run anything).
-  add_custom_target(coverage
+  add_custom_target(${AKSL_COVERAGE_TARGET}
     COMMAND ctest --test-dir ${CMAKE_CURRENT_BINARY_DIR} --output-on-failure
     COMMAND ${AKSL_COVERAGE_ARGS}
     WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
     USES_TERMINAL
     COMMENT "Running the test suite under gcov and reporting coverage"
   )
-  add_dependencies(coverage ${AKSL_TEST_TARGETS})
+  add_dependencies(${AKSL_COVERAGE_TARGET} ${AKSL_TEST_TARGETS})
 elseif(AKSL_COVERAGE)
   message(WARNING "AKSL_COVERAGE=ON but Python3 was not found: "
                   "instrumenting the build, but the coverage report "