S6: embedded TCP/MCP UI via IReaperUIEmbedInterface

Inline keymap/level strip drawn into REAPER's embed bitmap, reusing the LICE
idiom. Pure embed_strip layout/hit-test (tested); processor exposes the embed
interface off queryInterface and publishes an RT-safe block peak for the level.

CMakeLists.txt

@@ -621,6 +621,15 @@ target_include_directories(editor_geometry PUBLIC src/vst)
 add_library(bridge_marshal STATIC src/vst/bridge_marshal.cpp)
 target_include_directories(bridge_marshal PUBLIC src/vst)
 
+# embed_strip (Phase S6) — PURE layout + hit-test for the embedded TCP/MCP strip: the
+# 128-key span -> zone-segment rects, point -> zone selection, and the level-band fill.
+# The mirror of editor_geometry (whose Rect + contains() it reuses); unit-tested outside
+# the DAW, while the embed shell (src/vst/reasampler_embed.cpp) marshals REAPER's embed
+# messages (paint bitmap + mouse coords) into it. Links editor_geometry for the shared Rect.
+add_library(embed_strip STATIC src/vst/embed_strip.cpp)
+target_include_directories(embed_strip PUBLIC src/vst)
+target_link_libraries(embed_strip PUBLIC editor_geometry)
+
 # sample_map (Phase S4) — PURE mapping logic for the Tier-0 instrument: the live bank
 # blob -> selected sample (via the SHARED bank_book JSON parse, NOT a second parser),
 # interleaved->mono downmix (the Tier-0 channel policy), the Tier-0 chromatic keymap
@@ -641,6 +650,10 @@ add_executable(bridge_marshal_tests tests/test_bridge_marshal.cpp)
 target_link_libraries(bridge_marshal_tests PRIVATE bridge_marshal)
 add_test(NAME bridge_marshal_tests COMMAND bridge_marshal_tests)
 
+add_executable(embed_strip_tests tests/test_embed_strip.cpp)
+target_link_libraries(embed_strip_tests PRIVATE embed_strip)
+add_test(NAME embed_strip_tests COMMAND embed_strip_tests)
+
 # sample_map: the S4 mapping heart. Links ONLY sample_map (+ its pure deps) — NEITHER
 # the VST3 SDK nor the REAPER SDK — the same structural plain-data-boundary proof the
 # sampler_core test enforces.
@@ -800,6 +813,7 @@ if(WIN32)
         src/vst/vst_entry.cpp
         src/vst/reasampler_processor.cpp
         src/vst/reasampler_editor.cpp
+        src/vst/reasampler_embed.cpp
         src/vst/reaper_bridge.cpp
         # SDK module entry — compiled into the module (not the static lib) so the
         # InitDll/ExitDll dll exports survive the link (see vst3_sdk note above).
@@ -813,8 +827,10 @@ if(WIN32)
     # peaks) transitively. capture_paths: the shared M4 path resolution (resolveBankFile /
     # projectDirOfRpp) the bridge + processor use. Its PUBLIC include dirs (src, src/vst)
     # give the shell TUs their headers (ext_keys.h, bank_book.h, sampler_core.h, ...).
+    # embed_strip (S6): the pure inline-strip layout + hit-test the embed shell marshals
+    # into; it links editor_geometry transitively (shared Rect).
     target_link_libraries(reasampler_vst PRIVATE vst3_sdk editor_geometry bridge_marshal
-        sample_map capture_paths)
+        sample_map capture_paths embed_strip)
     # SDK_INC gives reaper_vst3_interfaces.h + reaper_plugin_functions.h for the bridge;
     # WDL_INC gives LICE for the editor. The VST3 SDK headers come from vst3_sdk PUBLIC.
     target_include_directories(reasampler_vst PRIVATE ${SDK_INC} ${WDL_INC})