test sweep: close small terminal coverage gaps (T-91)

Four targeted tests covering the last single-line/short-tail gaps
in the terminal tree: the PointerInputs.none / .all const
constructors, the abstract TerminalMouseHandler const constructor
(reached via a private subclass), the reflow-output-padding branch
in Buffer.resize (line < newHeight), and the wide-char skip in
TerminalPainter.paintLine.

Coverage: pointer_input 1/3 -> 3/3; mouse/handler 33/34 -> 34/34;
buffer/buffer 260/261 -> 261/261; painter 120/121 -> 121/121.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/terminal/coverage_trivials_test.dart

@@ -0,0 +1,59 @@
+/// Closeout tests for the last single-digit-uncovered lines in
+/// `lib/src/terminal/`: pointer_input constructors, the abstract
+/// TerminalMouseHandler constructor, the reflow padding branch in
+/// Buffer.resize, and the wide-char skip branch in
+/// TerminalPainter.paintLine.
+library;
+
+import 'dart:ui';
+
+import 'package:clide/src/terminal/src/core/mouse/handler.dart';
+import 'package:clide/src/terminal/src/terminal.dart';
+import 'package:clide/src/terminal/src/ui/painter.dart';
+import 'package:clide/src/terminal/src/ui/pointer_input.dart';
+import 'package:clide/src/terminal/src/ui/terminal_text_style.dart';
+import 'package:clide/src/terminal/src/ui/themes.dart';
+import 'package:flutter/painting.dart';
+import 'package:test/test.dart';
+
+class _StubMouseHandler extends TerminalMouseHandler {
+  const _StubMouseHandler();
+  @override
+  String? call(TerminalMouseEvent event) => null;
+}
+
+void main() {
+  test('PointerInputs.none / .all produce expected sets', () {
+    expect(const PointerInputs.none().inputs, isEmpty);
+    expect(const PointerInputs.all().inputs, containsAll(PointerInput.values));
+  });
+
+  test('TerminalMouseHandler abstract const constructor is reachable via a subclass', () {
+    const h = _StubMouseHandler();
+    expect(h, isA<TerminalMouseHandler>());
+  });
+
+  test('Buffer.resize pads reflow output up to the new height', () {
+    final t = Terminal(maxLines: 200, onOutput: (_) {});
+    // Write content narrower than the new width — reflow should produce
+    // fewer lines than newHeight, triggering the pad-with-empty-lines
+    // branch in buffer.dart.
+    t.write('abc\r\n');
+    // Resize to a wide + tall viewport.
+    t.resize(40, 50, 8, 16);
+    expect(t.buffer.lines.length, greaterThanOrEqualTo(50));
+  });
+
+  test('TerminalPainter.paintLine handles wide (CJK) cells without skipping the skip', () {
+    final t = Terminal(maxLines: 100, onOutput: (_) {});
+    // CJK ideograph — terminal stores it as a width-2 cell, so paintLine
+    // advances `i` twice and the wide-char branch fires.
+    t.write('漢字');
+    final p = TerminalPainter(
+      theme: TerminalThemes.defaultTheme,
+      textStyle: const TerminalStyle(),
+      textScaler: const TextScaler.linear(1.0),
+    );
+    p.paintLine(Canvas(PictureRecorder()), Offset.zero, t.buffer.lines[0]);
+  });
+}