tui: remove debug/test-only crate features (#16457)

## Why

The remaining `vt100-tests` and `debug-logs` features in `codex-tui`
were only gating test-only and debug-only behavior. Those feature
toggles add Cargo and Bazel permutations without buying anything, and
they make it easier for more crate features to linger in the workspace.

## What changed

- delete `vt100-tests` and `debug-logs` from `codex-tui`
- always compile the VT100 integration tests in the TUI test target
instead of hiding them behind a Cargo feature
- remove the unused textarea debug logging branch instead of replacing
it with another gate
- add the required argument-comment annotations in the VT100 tests now
that Bazel sees those callsites during linting
- shrink the manifest verifier allowlist again so only the remaining
real feature exceptions stay permitted

## How tested

- `cargo test -p codex-tui`
- `just argument-comment-lint -p codex-tui`

codex-rs/tui/src/bottom_pane/textarea.rs

@@ -529,10 +529,7 @@ impl TextArea {
             } => {
                 self.move_cursor_to_end_of_line(/*move_down_at_eol*/ true);
             }
-            _o => {
-                #[cfg(feature = "debug-logs")]
-                tracing::debug!("Unhandled key event in TextArea: {:?}", _o);
-            }
+            _ => {}
         }
     }