phase 1: cleanup, REPL polish, README

- fix format-string in jprint/script_print (printf(msg) -> fputs)
- fix bsexp_deinit: deinit_script guarded by sctx, not jc
- silence "config.script not found" when the optional override is absent
- remove dead code: bs/cmds/, bs/args.{c,h}, bs/utils.h, commented blocks
- REPL: welcome banner with version, readline tab-completion on
  script_commands_list, skip blank lines, clean Ctrl-D exit
- README: build, REPL usage, typical SPI flow, command table, probes,
  Xilinx STARTUPE3/CCLK caveat

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

bs/init.h

@@ -3,17 +3,8 @@
 
 #include "config/bs_defines.h"
 
-typedef int (*command_call)(jtag_core *jc, int argc, char *argv[]);
-
-typedef struct {
-    char *name;
-    command_call cmd_call;
-} Command;
-
-extern Command commands[];
-
 int script_print(script_ctx *sctx, enum MSGTYPE typ, char *string, ...);
 void bsexp_init(jtag_core **jc, script_ctx **sctx);
 void bsexp_deinit(jtag_core *jc, script_ctx *sctx);
 
-#endif
+#endif