shell: ^C cancels the line / aborts streams, ^D = EOF → poweroff

- ps2: Ctrl+C and Ctrl+D are now KeyEvents (ctrl modifier + c/d map);
  other Ctrl+key combos are swallowed
- shell read_line: ^C clears the line and echoes '^C' (bash-style),
  ^D on an empty line echoes '^D' and shuts down (EOF), ^D with text
  on the line is ignored
- cat/hexdump stream incrementally (was: build whole string then print)
  and check for ^C between chunks, so a running dump can be aborted
- verified in QEMU: line cancel, standalone interrupt, ^C aborts an
  infinite 'cat /dev/zero' stream, ^D powers off

1 files changed, 3 insertions, 0 deletions

diff --git a/CONTEXT.md b/CONTEXT.md
index 5b76eaa..66ab320 100644
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -130,6 +130,9 @@ Single Rust crate (`x86_64-unknown-uefi` target).  Module breakdown:
 ✅ **VFS** — “everything is a file”: dirs, ramfs, char devices
   (`ls`/`cat`/`hexdump`/`mkdir`/`touch`/`rm`, `echo >`/`>>`; devices
   regenerate on read, `/dev/mem` is raw physical RAM)
+✅ **^C / ^D** — Ctrl+C cancels the line or aborts a running stream
+  (`cat`/`hexdump` check between chunks), Ctrl+D on an empty line
+  powers off (EOF)
 
 ## Target audience