Add CLI argument and validate rows to flow behavior matrix

- Add rows for --ignore-user-messages, --ignore-pre-action-messages,
  and --ignore-post-action-messages
- Add row for winget validate (schema check only, no rendering)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: denelon

doc/specs/#3483 - UserMessages.md

@@ -163,6 +163,10 @@ Post-action messages are displayed in both interactive and non-interactive modes
 | `disableInstallNotes` setting enabled | `Pre*` still shown (not affected) | `Post*` still shown (controlled by `userMessages` settings, not `disableInstallNotes`) | Legacy setting does not affect new fields |
 | `userMessages.disablePostActionMessages` enabled | `Pre*` still shown | `Post*` suppressed | New setting for new fields |
 | `userMessages.disablePreActionMessages` enabled | `Pre*` suppressed, no prompt | `Post*` still shown | Suppresses both display and prompt |
+| `--ignore-user-messages` | `Pre*` suppressed, no prompt | `Post*` suppressed | CLI argument overrides settings for this invocation |
+| `--ignore-pre-action-messages` | `Pre*` suppressed, no prompt | `Post*` still shown | CLI argument overrides `disablePreActionMessages` setting |
+| `--ignore-post-action-messages` | `Pre*` still shown | `Post*` suppressed | CLI argument overrides `disablePostActionMessages` setting |
+| `winget validate` | Not shown, not prompted | Not shown | Validation checks schema correctness only; messages are not rendered |
 
 #### Bulk Operations (`upgrade --all`, `import`)