test(13-03): add failing tests for Input and Textarea components (RED)

- TestInput_DefaultType: expects type="text" for empty Type
- TestInput_EmailType: expects type="email" for explicit Type
- TestInput_IDFallback: expects id from Name when no ID set
- TestInput_ExplicitID: expects explicit ID to take precedence
- TestTextarea_RendersClass: expects class="ui-textarea"
- TestTextarea_DefaultRows: expects rows="4" for zero Rows
- TestTextarea_ExplicitRows: expects rows="6" for explicit Rows

backend/internal/web/ui/ui_test.go

@@ -226,3 +226,57 @@ func TestBadge_PrimaryVariant(t *testing.T) {
 		t.Errorf("expected ui-badge-primary in output; got: %s", out)
 	}
 }
+
+// Phase 13 Plan 03 — Input and Textarea component tests (TDD RED)
+
+func TestInput_DefaultType(t *testing.T) {
+	out := render(t, context.Background(), Input(InputProps{Name: "x"}))
+	if !strings.Contains(out, `type="text"`) {
+		t.Errorf("expected type=\"text\" for empty Type; got: %s", out)
+	}
+	if !strings.Contains(out, `class="ui-input"`) {
+		t.Errorf("expected class=\"ui-input\"; got: %s", out)
+	}
+}
+
+func TestInput_EmailType(t *testing.T) {
+	out := render(t, context.Background(), Input(InputProps{Name: "email", Type: "email"}))
+	if !strings.Contains(out, `type="email"`) {
+		t.Errorf("expected type=\"email\"; got: %s", out)
+	}
+}
+
+func TestInput_IDFallback(t *testing.T) {
+	out := render(t, context.Background(), Input(InputProps{Name: "email"}))
+	if !strings.Contains(out, `id="email"`) {
+		t.Errorf("expected id=\"email\" (fallback from name); got: %s", out)
+	}
+}
+
+func TestInput_ExplicitID(t *testing.T) {
+	out := render(t, context.Background(), Input(InputProps{ID: "my-id", Name: "x"}))
+	if !strings.Contains(out, `id="my-id"`) {
+		t.Errorf("expected id=\"my-id\"; got: %s", out)
+	}
+}
+
+func TestTextarea_RendersClass(t *testing.T) {
+	out := render(t, context.Background(), Textarea(TextareaProps{Name: "body"}))
+	if !strings.Contains(out, `class="ui-textarea"`) {
+		t.Errorf("expected class=\"ui-textarea\"; got: %s", out)
+	}
+}
+
+func TestTextarea_DefaultRows(t *testing.T) {
+	out := render(t, context.Background(), Textarea(TextareaProps{Name: "x", Rows: 0}))
+	if !strings.Contains(out, `rows="4"`) {
+		t.Errorf("expected rows=\"4\" for zero Rows; got: %s", out)
+	}
+}
+
+func TestTextarea_ExplicitRows(t *testing.T) {
+	out := render(t, context.Background(), Textarea(TextareaProps{Name: "x", Rows: 6}))
+	if !strings.Contains(out, `rows="6"`) {
+		t.Errorf("expected rows=\"6\"; got: %s", out)
+	}
+}