P5: F5b — exp2 0x26b820 assets extracted bit-exact + numeric fallback exp2_dsp

Extracted the 8x16 irrational tables + lead-in -708.4xx series from soothe_mem.bin
into exp2_tables.{hpp,cpp} (P3 bit-exact inputs). exp2_dsp = numerically-correct
double exp2 matching std::exp2 (wiring fallback; NOT bit-exact yet — the plugin
body has special subnormal/overflow branches and a vfmadd213sd poly not yet 1:1).
exp2_check: 2e6-grid PASS (0 cells >1e-13).

dsp/CMakeLists.txt

@@ -20,6 +20,8 @@ add_library(soothe2_dsp SHARED
     phase_table.cpp
     fftconv.cpp
     vlog.cpp
+    exp2_tables.cpp
+    exp2.cpp
     leveltrack.cpp
     framed_model.cpp
     rt_weights.cpp
@@ -34,8 +36,10 @@ add_executable(fftconv_check fftconv_check.cpp)
 add_executable(vlog_check vlog_check.cpp)
 add_executable(leveltrack_check leveltrack_check.cpp)
 add_executable(levelpath_check levelpath_check.cpp)
+add_executable(exp2_check exp2_check.cpp)
 target_link_libraries(twin_check soothe2_dsp)
 target_link_libraries(framed_test soothe2_dsp)
+target_link_libraries(exp2_check soothe2_dsp)
 target_link_libraries(tables_check soothe2_dsp)
 target_link_libraries(fftconv_check soothe2_dsp)
 target_link_libraries(vlog_check soothe2_dsp)