[M2] add SQLite overlay + add_manual

CMakeLists.txt

@@ -29,6 +29,8 @@ if(CARGOXX_WERROR)
     add_compile_options(-Werror)
 endif()
 
+find_package(SQLite3 REQUIRED)
+
 # ----- cargoxx library: module units + implementation units -----
 add_library(cargoxx STATIC)
 target_include_directories(cargoxx SYSTEM PRIVATE third_party)
@@ -44,6 +46,7 @@ target_sources(cargoxx
         src/layout/layout.cpp
         src/linkdb/recipe.cpp
         src/linkdb/curated.cpp
+        src/linkdb/overlay.cpp
         src/cli/cmd_new.cpp
         src/cli/run.cpp
     PUBLIC
@@ -60,6 +63,8 @@ target_sources(cargoxx
             src/cli/cli.cppm
 )
 
+target_link_libraries(cargoxx PRIVATE SQLite::SQLite3)
+
 # ----- cargoxx binary -----
 add_executable(cargoxx_bin src/main.cpp)
 set_target_properties(cargoxx_bin PROPERTIES OUTPUT_NAME cargoxx)