feat(bank_panel): B4 vertical-split UI — LICE tab strip, id-keyed bank ops, move/copy drag

Pool grid on top, LICE-drawn named-banks tab strip below with overflow-scroll
(new pure tab_strip seam, unit-tested). Full-height toggles, unmistakable
active-bank readout distinct from the shown tab, tab context menu
(activate/rename/delete/evacuate/create) with rich confirm-on-non-empty-delete,
and move/copy via menu + drag with drop-highlighting. Fold-in: deserialize
auto-disambiguates duplicate folded bank names instead of rejecting the book.

CMakeLists.txt

@@ -55,6 +55,17 @@ target_include_directories(bank_grid PUBLIC src)
 add_library(mode_switch STATIC src/mode_switch.cpp)
 target_include_directories(mode_switch PUBLIC src)
 
+# ---------------------------------------------------------------------------
+# 2c'') Pure tab_strip layout — NO REAPER, NO SWELL. The named-banks tab-strip
+#       geometry (B4): strip rect + N tabs at a fixed tab width + scroll offset ->
+#       per-tab rects (overflow-clipped), overflow chevron reservation + maxScroll,
+#       and point -> tab / chevron hit-test. Split out so the strip's layout +
+#       overflow/scroll math is unit-tested outside the DAW; the bank_panel region
+#       that draws it and routes clicks is DAW-verified. Mirror of mode_switch.
+# ---------------------------------------------------------------------------
+add_library(tab_strip STATIC src/tab_strip.cpp)
+target_include_directories(tab_strip PUBLIC src)
+
 # ---------------------------------------------------------------------------
 # 2d) Pure view_mode_model library — NO REAPER, NO SWELL. The Design View heart
 #     (Phase D1): mode registry + GUID-keyed membership index + folder-tree-aware
@@ -156,6 +167,10 @@ add_executable(mode_switch_tests tests/test_mode_switch.cpp)
 target_link_libraries(mode_switch_tests PRIVATE mode_switch)
 add_test(NAME mode_switch_tests COMMAND mode_switch_tests)
 
+add_executable(tab_strip_tests tests/test_tab_strip.cpp)
+target_link_libraries(tab_strip_tests PRIVATE tab_strip)
+add_test(NAME tab_strip_tests COMMAND tab_strip_tests)
+
 add_executable(view_mode_model_tests tests/test_view_mode_model.cpp)
 target_link_libraries(view_mode_model_tests PRIVATE view_mode_model)
 add_test(NAME view_mode_model_tests COMMAND view_mode_model_tests)
@@ -206,6 +221,7 @@ add_library(reaper_reasampler MODULE
     src/persist.cpp
     src/bank_panel.cpp
     src/mode_switch.cpp
+    src/tab_strip.cpp
     src/insert.cpp
     src/insert_plan.cpp
     ${LICE_SRC}
@@ -216,7 +232,7 @@ add_library(reaper_reasampler MODULE
     src/actions.cpp
     src/bank_book.cpp
 )
-target_link_libraries(reaper_reasampler PRIVATE bank_model capture_paths peaks bank_grid mode_switch view_mode_model insert_plan render_settings tail_control realtime_record bank_book)
+target_link_libraries(reaper_reasampler PRIVATE bank_model capture_paths peaks bank_grid mode_switch tab_strip view_mode_model insert_plan render_settings tail_control realtime_record bank_book)
 target_include_directories(reaper_reasampler PRIVATE ${SDK_INC} ${WDL_INC})
 set_target_properties(reaper_reasampler PROPERTIES PREFIX "" OUTPUT_NAME "reaper_reasampler")