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, 16 insertions, 2 deletions

diff --git a/src/proc.asm b/src/proc.asm
index ab1c807..cd79160 100644
--- a/src/proc.asm
+++ b/src/proc.asm
@@ -224,7 +224,9 @@ ProcCreate::
     ld [hl+], a                 ; PROC_EXIT
     ld a, STD_CONSOLE
     ld [hl+], a                 ; PROC_STDIN  = console
-    ld [hl], a                  ; PROC_STDOUT = console
+    ld [hl+], a                 ; PROC_STDOUT = console
+    ld a, $FF
+    ld [hl], a                  ; PROC_PROG   = none
 
     ; build the initial stack frame in the task's RAM bank
     ld a, [wTmpEntry]
@@ -453,7 +455,10 @@ sys_fork::
     ld [hl+], a                 ; child STDIN = parent STDIN
     inc de
     ld a, [de]
-    ld [hl], a                  ; child STDOUT = parent STDOUT
+    ld [hl+], a                 ; child STDOUT = parent STDOUT
+    inc de
+    ld a, [de]
+    ld [hl], a                  ; child PROC_PROG = parent PROC_PROG
 
     ; ---- return to the parent with child pid ----
     ld a, [wForkUserSP]
@@ -484,6 +489,15 @@ sys_fork::
 ; our demo programs keep no pre-initialized RAM.
 ; =============================================================================
 sys_exec::
+    ; record the running program id in the PCB (for ps)
+    ld a, [wCurProc]
+    add PROC_PROG
+    ld l, a
+    ld a, [wCurProc+1]
+    adc 0
+    ld h, a
+    ld a, b
+    ld [hl], a
     ; HL = &ProgramTable[B] = ProgramTable + B*4
     ld hl, ProgramTable
     ld a, b