Added:

- Toolchain overrides via `[toolchain]` and env (`DCR_*`)
- ASM `.S` preprocessing via GCC/Clang (`-x assembler-with-cpp`)

TODO.md

@@ -3,7 +3,5 @@
 - Add header dependency tracking for incremental builds (GCC/Clang: -MMD, MSVC: /showIncludes)
 - Add external package managers (Conan, vcpkg)
 - Multi-target
-- ASM support
 - Linker script + direct linker control
-- Custom targets/steps
-- Tool overrides and env vars
+- Custom targets/steps