fix: address lint findings from rebase

- Replace string concat loop with strings.Repeat (perfsprint)
- Use require.Positive/assert.Positive instead of Greater(x, 0) (testifylint)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: cpcloud

internal/app/extraction_render.go

@@ -164,9 +164,8 @@ func (m *Model) buildExtractionPipelineOverlay(
 			// doesn't shrink when a shorter tab is displayed.
 			actualLines := strings.Count(previewSection, "\n")
 			targetLines := previewLines - 2 // -2: sep+blank added as separate parts
-			for actualLines < targetLines {
-				previewSection += "\n"
-				actualLines++
+			if pad := targetLines - actualLines; pad > 0 {
+				previewSection += strings.Repeat("\n", pad)
 			}
 		}
 	}

internal/app/extraction_test.go

@@ -3667,9 +3667,9 @@ func TestExploreMode_HintBarTrailingOrder(t *testing.T) {
 	pipelineAcceptIdx := hintIndex(pipelinePlain, "accept")
 	pipelineExploreIdx := hintIndex(pipelinePlain, "explore")
 	pipelineEscIdx := hintIndex(pipelinePlain, "discard")
-	require.Greater(t, pipelineAcceptIdx, 0, "accept hint should appear")
-	require.Greater(t, pipelineExploreIdx, 0, "explore hint should appear")
-	require.Greater(t, pipelineEscIdx, 0, "discard hint should appear")
+	require.Positive(t, pipelineAcceptIdx, "accept hint should appear")
+	require.Positive(t, pipelineExploreIdx, "explore hint should appear")
+	require.Positive(t, pipelineEscIdx, "discard hint should appear")
 	assert.Less(t, pipelineAcceptIdx, pipelineExploreIdx,
 		"accept should come before explore")
 	assert.Less(t, pipelineExploreIdx, pipelineEscIdx,
@@ -3804,7 +3804,7 @@ func TestExploreMode_UnknownTableOverlayStable(t *testing.T) {
 	plain := ansi.Strip(out)
 	lines := strings.Count(out, "\n")
 
-	assert.Greater(t, lines, 0, "overlay should render with nonzero height")
+	assert.Positive(t, lines, "overlay should render with nonzero height")
 	assert.Contains(t, plain, "no operations",
 		"should show fallback text for unknown tables")