kill + ps: implement SYS_KILL (pid 1 immortal) and a ps tool

- PCB gains PROC_PROG (running program id), set by exec, inherited on fork.
- sys_kill(pid): reject pid 1 (immortal) and unknown/dead pids; mark the target
  zombie, reparent its children to init, wake its parent if blocked in wait;
  schedule away if a process kills itself. Reuses FindPcbByPid/ReparentToInit.
- sys_ps(slot,buf)->{pid,state,prog}; sys_progname(id) via NameTable reverse
  lookup. NameTable gains sh/ps/kill.
- libc: kill/psget/progname; tools ps (pid state cmd) and kill <pid>.
- verified: ps lists sh(B)+ps(R); kill 1 refused; kill 42 fails.

1 files changed, 20 insertions, 0 deletions

diff --git a/c/libc.s b/c/libc.s
index 857a16d..bcc8199 100644
--- a/c/libc.s
+++ b/c/libc.s
@@ -167,3 +167,23 @@ _lookup:
 	ld	c, #19			; SYS_LOOKUP
 	rst	#0x30
 	ret
+
+	.globl _kill, _psget, _progname
+	;; unsigned char kill(unsigned char pid /*A*/) -> A (0 ok, $FF fail)
+_kill:
+	ld	b, a
+	ld	c, #9			; SYS_KILL
+	rst	#0x30
+	ret
+	;; unsigned char psget(unsigned char slot /*A*/, unsigned char *buf /*DE*/) -> A
+_psget:
+	ld	b, a
+	ld	c, #20			; SYS_PS
+	rst	#0x30
+	ret
+	;; void progname(unsigned char id /*A*/, char *buf /*DE*/)
+_progname:
+	ld	b, a
+	ld	c, #21			; SYS_PROGNAME
+	rst	#0x30
+	ret