svf: extract player core into standalone libsvf, keep bscan glue

The SVF player now lives in electronics/libsvf behind a five-function
JTAG ops table, shared with the wifi_jtag_programmer Zephyr firmware.
src/modules/svf/ shrinks to the bscan_*-backed port (bs_svf_play),
which also keeps the FTDI stale-FIFO warm-up. Local checkout override:
-DFETCHCONTENT_SOURCE_DIR_SVF=<path>.

CMakeLists.txt

@@ -19,6 +19,15 @@ FetchContent_Declare(bsdl
 )
 FetchContent_MakeAvailable(bsdl)
 
+# ---- libsvf (SVF player, extracted from this repo and now standalone) ----
+# Same pattern as libbsdl. Local checkout override:
+# -DFETCHCONTENT_SOURCE_DIR_SVF=/path/to/libsvf
+FetchContent_Declare(svf
+    GIT_REPOSITORY ssh://gitea@git.beafrancois.fr:8329/electronics/libsvf.git
+    GIT_TAG        main
+)
+FetchContent_MakeAvailable(svf)
+
 # Digilent JTAG-SMT* backend. The driver dlopen's libdjtg/libdmgr at
 # runtime and degrades to "no probe" if they're absent, so building it
 # in costs nothing — default ON. Needs <dlfcn.h>, so UNIX only.