bscan: rename from bscan_spi, add TAP primitives for the SVF player

The module outgrew its "SPI bridge" name — it's mostly generic
single-device JTAG TAP primitives now. Rename modules/bscan_spi ->
modules/bscan (dir, files, library target, includes, doc paths);
bscan_* function names and bscan_spi_xfer() kept.

Add the two primitives the SVF player needs beyond shift_dr:
- bscan_shift_ir: general IR scan with TDO capture (bscan_set_ir is
  opcode-only, no readback)
- bscan_tap_reset: force Test-Logic-Reset, land in Run-Test/Idle

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

modules/script/script.c

@@ -39,7 +39,7 @@
 #include "os_interface/os_interface.h"
 #include "fpga/fpga.h"
 #include "probes/probes.h"
-#include "bscan_spi/bscan_spi.h"
+#include "bscan/bscan.h"
 #include "spi_flash/spi_flash.h"
 
 #include "env.h"