Add fresh CMake/platform scaffolding, core engine, and SDL3 window

Platform folders, cmake target/option/platform detection, Linux and PSP
scripts and Docker setup, assert/util/thread/error/log/perf/time/console/
engine/display modules, and an SDL3 window cleared to red.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

cmake/option.cmake

@@ -0,0 +1,40 @@
+# Copyright (c) 2026 Dominic Masters
+#
+# This software is released under the MIT License.
+# https://opensource.org/licenses/MIT
+
+# All user facing CMake options and their defaults. Included by the root
+# CMakeLists.txt after the platform's target.cmake, which supplies the
+# DUSK_DEFAULT_* values used below. DUSK_TARGET_SYSTEM itself is declared by
+# determineplatform.cmake.
+
+# General
+option(DUSK_BUILD_TESTS "Enable tests." OFF)
+option(DUSK_NETWORK "Enable network support." ON)
+
+# Game metadata
+set(DUSK_GAME_NAME "Dusk" CACHE STRING "Game display name.")
+set(DUSK_GAME_AUTHOR "YourWishes" CACHE STRING "Game author / coder.")
+if(NOT DEFINED DUSK_VERSION)
+  string(TIMESTAMP DUSK_VERSION "debug-%y%m%d%H%M%S")
+endif()
+
+# Platform dependent defaults
+option(DUSK_ASSERTIONS_FAKED
+  "Compile assertions out (they do nothing)."
+  ${DUSK_DEFAULT_ASSERTIONS_FAKED}
+)
+option(DUSK_BACKTRACE
+  "Log a stack trace on assertion failure."
+  ${DUSK_DEFAULT_BACKTRACE}
+)
+option(DUSK_TRACK_MEMORY
+  "Track memoryAllocate() call sites to help find memory leaks."
+  ${DUSK_DEFAULT_TRACK_MEMORY}
+)
+
+# Tests mock assertions, so they can never be faked.
+if(DUSK_BUILD_TESTS AND DUSK_ASSERTIONS_FAKED)
+  message(STATUS "DUSK_BUILD_TESTS: forcing DUSK_ASSERTIONS_FAKED off")
+  set(DUSK_ASSERTIONS_FAKED OFF CACHE BOOL "" FORCE)
+endif()