Repair embedded dependency build and test setup

Isolate vendored test registration, namespace project error codes, and update dependency revisions. Fix mutable sprite path handling, out-of-tree fixtures, and charviewer initialization while documenting the outstanding character-to-sprite refcount bug.

Co-authored-by: Codex (GPT-5) <noreply@openai.com>

CMakeLists.txt

@@ -4,7 +4,25 @@ project(akgl LANGUAGES C)
 include(CTest)
 
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-  
+
+# Vendored projects own their test suites. Suppress their CTest registration
+# while embedded so the top-level suite contains only targets built here.
+set(AKGL_SUPPRESS_DEPENDENCY_TESTS TRUE)
+function(add_test)
+  if(NOT AKGL_SUPPRESS_DEPENDENCY_TESTS)
+    _add_test(${ARGV})
+  endif()
+endfunction()
+function(set_tests_properties)
+  if(NOT AKGL_SUPPRESS_DEPENDENCY_TESTS)
+    _set_tests_properties(${ARGV})
+  endif()
+endfunction()
+
+set(JANSSON_WITHOUT_TESTS ON CACHE BOOL "Do not build vendored Jansson tests" FORCE)
+set(JANSSON_EXAMPLES OFF CACHE BOOL "Do not build vendored Jansson examples" FORCE)
+set(JANSSON_BUILD_DOCS OFF CACHE BOOL "Do not build vendored Jansson docs" FORCE)
+
 add_subdirectory(deps/jansson EXCLUDE_FROM_ALL)
 add_subdirectory(deps/libakerror EXCLUDE_FROM_ALL)
 add_subdirectory(deps/libakstdlib EXCLUDE_FROM_ALL)
@@ -13,6 +31,13 @@ add_subdirectory(deps/SDL_image EXCLUDE_FROM_ALL)
 add_subdirectory(deps/SDL_mixer EXCLUDE_FROM_ALL)
 add_subdirectory(deps/SDL_ttf EXCLUDE_FROM_ALL)
 
+# Reserve error-name table entries for libakgl-specific status codes.
+target_compile_definitions(akerror PUBLIC
+  AKERR_MAX_ERR_VALUE=256
+)
+
+set(AKGL_SUPPRESS_DEPENDENCY_TESTS FALSE)
+
 else()
 
   find_package(PkgConfig REQUIRED)
@@ -48,6 +73,11 @@ set(libdir      "\${exec_prefix}/lib")
 set(includedir  "\${prefix}/include")
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/akgl.pc.in ${CMAKE_CURRENT_BINARY_DIR}/akgl.pc @ONLY)
 
+# Tests use both relative paths and SDL_GetBasePath(), so stage fixtures beside
+# test executables in every out-of-tree build.
+file(COPY "${CMAKE_CURRENT_SOURCE_DIR}/tests/assets"
+     DESTINATION "${CMAKE_CURRENT_BINARY_DIR}")
+
 add_custom_command(
   OUTPUT ${GAMECONTROLLERDB_H}
   COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/mkcontrollermappings.sh ${CMAKE_CURRENT_SOURCE_DIR}
@@ -100,6 +130,11 @@ add_test(NAME tilemap COMMAND test_tilemap)
 add_test(NAME util COMMAND test_util)
 add_test(NAME semver_unit COMMAND test_semver_unit)
 
+set_tests_properties(
+  actor bitmasks character registry sprite staticstring tilemap util semver_unit
+  PROPERTIES WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/tests"
+)
+
 # Specify include directories for the library's headers (if applicable)
 target_include_directories(akgl PUBLIC
   include/