vim: document the VICE command checks

NOTES records the dd/p, A/I/O/o, :q/:q! and missing-file checks that pass
on the work disk, and that \x03 in -keybuf arrives as RUN/STOP so a script
can leave insert mode.

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vim/NOTES.md

@@ -180,3 +180,18 @@ on the status row (since removed):
 - Keep a screenshot of every build step (`shots\cc-*.png`, `link.png`) and make
   the script fail *per step* ("cc vim.c produced no object") instead of at the
   end, or a compile failure looks like a linker failure.
+
+## Verified in VICE
+
+The editing commands were driven from `build.ps1 -Keys` against a scratch file
+(`ALPHA`/`BRAVO`/`CHARLIE`/`DELTA` on `work.d81`), then read back with `c1541`
+and compared:
+
+- `dd` removes the current line and `p` puts it below the next one.
+- `A`, `I`, `O` and `o` insert where they should; RUN/STOP leaves insert mode.
+- `:q` on a dirty buffer refuses with `unsaved - :q! quits`; `:q!` quits and
+  leaves the file alone.
+- A missing file prompts `not found - create it? (y/n)`: `y` starts an empty
+  buffer that `:wq` creates, `n` goes back to the `file:` prompt.
+- `\x03` in `-keybuf` arrives as RUN/STOP (PETSCII `$03`), so a script can
+  leave insert mode.