Initial extraction: C++ MixerEngine standalone daemon

Extracted from op-pedal mixer-engine branch. Core components:

- MixerEngine / MixerChannelStrip / MixerBus — cleaned of LV2/Pedalboard/IHost/MidiMapper deps
- MixerControlServer — Unix domain socket JSON control interface
- main.cpp — JACK audio I/O client with headless fallback
- CMake build — auto-fetches nlohmann/json, links JACK
- 9 core tests passing

Architecture: JACK ports → MixerEngine::process() → JACK ports,
controlled via Unix socket JSON commands.

build/CMakeFiles/mixer-daemon.dir/DependInfo.cmake

@@ -0,0 +1,24 @@
+
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+
+# The set of languages for which implicit dependencies are needed:
+set(CMAKE_DEPENDS_LANGUAGES
+  )
+
+# The set of dependency files which are needed:
+set(CMAKE_DEPENDS_DEPENDENCY_FILES
+  "/home/oplabs/projects/oplabs-mixer-daemon/src/main.cpp" "CMakeFiles/mixer-daemon.dir/src/main.cpp.o" "gcc" "CMakeFiles/mixer-daemon.dir/src/main.cpp.o.d"
+  "" "mixer-daemon" "gcc" "CMakeFiles/mixer-daemon.dir/link.d"
+  )
+
+# Targets to which this target links which contain Fortran sources.
+set(CMAKE_Fortran_TARGET_LINKED_INFO_FILES
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+
+# Targets to which this target links which contain Fortran sources.
+set(CMAKE_Fortran_TARGET_FORWARD_LINKED_INFO_FILES
+  )
+
+# Fortran module output directory.
+set(CMAKE_Fortran_TARGET_MODULE_DIR "")