rsnix: preemptive kernel tasks (ADR 0003) — sched, IST fault stacks, 176-byte frames

- sched: 16-slot static table, shell=task 0, idle=task 1, spawn with
  guard page + 8 KiB stack, RR on the 100 Hz tick, int 0x60 yield,
  sleep_ms, lazy reap, jobs/bg/sleep/kill shell commands
- gdt: own GDT mirroring UEFI selectors + TSS with IST1/IST2
  (guard-page overflows die gracefully instead of triple-faulting)
- interrupts: isr_dispatch returns next frame in rax; IntFrame grows
  rsp/ss fields — QEMU's 64-bit iretq always pops all five slots from
  a 176-byte frame, so synthetic task frames must carry rsp=top+ss
  (a 160-byte frame made the first iretq pop rsp/ss from the unmapped
  page beyond the frame)
- panic handler: task panics abort the task, shell keeps running
- main: sched::init moved after page allocator + adopted tables
  (the idle's stack+guard need both; it was silently not spawning)

1 files changed, 3 insertions, 3 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 7b1ced6..2931bd6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4,7 +4,7 @@ version = 4
 
 [[package]]
 name = "rsdos"
-version = "0.2.0"
+version = "0.3.0"
 dependencies = [
  "rsnix",
  "shell",
@@ -19,11 +19,11 @@ dependencies = [
 
 [[package]]
 name = "rsnix"
-version = "0.2.0"
+version = "0.3.0"
 
 [[package]]
 name = "shell"
-version = "0.2.0"
+version = "0.3.0"
 dependencies = [
  "rsdosedit",
  "rsnix",