Close the FX reclaim span when REAPER's own Undo/Redo is dispatched, so the switch's point mints first

Both command hooks intercept Edit: Undo (40029) and Edit: Redo (40030) and consume
nothing. Undo routes that never dispatch an action remain uncovered.

src/app/CMakeLists.txt

@@ -39,6 +39,7 @@ add_library(reaper_reasampler MODULE
     ${LICE_SRC}
     ${REASAMPLER_SRC_DIR}/shell/capture/insert.cpp
     ${REASAMPLER_SRC_DIR}/shell/undo/undo_block.cpp
+    ${REASAMPLER_SRC_DIR}/shell/undo/undo_intercept.cpp
     ${REASAMPLER_SRC_DIR}/shell/undo/undo_trace.cpp
     ${REASAMPLER_SRC_DIR}/shell/view/view.cpp
     ${REASAMPLER_SRC_DIR}/shell/view/fx_reclaim.cpp
@@ -78,6 +79,10 @@ reasampler_test(view_reconcile LINK applied_state view_mode_model)
 # The reclaimer's drain loop is templated on its host for exactly this reason: the
 # ordering, budget, debounce and resume bookkeeping run against a fake chain.
 reasampler_test(fx_reclaim LINK fx_state)
+# Which dispatched action id ends the span. Header-only and SDK-free, so it links nothing;
+# src/shell/undo has no CMakeLists of its own for the same reason src/shell/view has none.
+add_executable(undo_intercept_tests ${REASAMPLER_TESTS_DIR}/test_undo_intercept.cpp)
+add_test(NAME undo_intercept_tests COMMAND undo_intercept_tests)
 
 # Bank-package import: the promptless verb plus its action skin. Kept as its own
 # appended block rather than merged into the lists above, so the two package