Naming, layout and comments: descriptive full-word names, one item per line in wrapped calls and literals, and doc comments on exported names

Short and single-letter names in application code become full words (tests
keep theirs). Wrapped calls, signatures and composite literals put one item
per line, and one-line function bodies are expanded. Exported names and
groups of constants get doc comments, and comments refer to the renamed
identifiers.

internal/cli/migrate/migrate_test.go

@@ -55,7 +55,9 @@ func TestMigrateUpCreateThenStatus(t *testing.T) {
 	latest := latestVersion(t)
 
 	out := mustRun(t, "migrate", "up", "--create")
-	cmdtest.Contains(t, out,
+	cmdtest.Contains(
+		t,
+		out,
 		"applied   00001_create_opportunities_table.sql",
 		fmt.Sprintf("Database migrated to version %d", latest),
 	)
@@ -64,7 +66,9 @@ func TestMigrateUpCreateThenStatus(t *testing.T) {
 	}
 
 	out = mustRun(t, "migrate", "status")
-	cmdtest.Contains(t, out,
+	cmdtest.Contains(
+		t,
+		out,
 		fmt.Sprintf("Database version %d of %d (up-to-date)", latest, latest),
 		"00001_create_opportunities_table.sql",
 	)
@@ -87,8 +91,11 @@ func TestMigrateUpAsksBeforeCreating(t *testing.T) {
 
 	out, err := run(t, "n\n", "migrate", "up")
 	cmdtest.ErrContains(t, err, "no database file")
-	cmdtest.Contains(t, out,
-		"Database file './test.db' does not exist. Would you like to create it?")
+	cmdtest.Contains(
+		t,
+		out,
+		"Database file './test.db' does not exist. Would you like to create it?",
+	)
 	if cmdtest.Exists("test.db") {
 		t.Error("test.db was created after answering no")
 	}
@@ -110,8 +117,11 @@ func TestMigrateUpBySteps(t *testing.T) {
 	cmdtest.Contains(t, out, "Database migrated to version 2")
 
 	out = mustRun(t, "migrate", "status")
-	cmdtest.Contains(t, out,
-		fmt.Sprintf("Database version 2 of %d (%d pending)", latest, latest-2))
+	cmdtest.Contains(
+		t,
+		out,
+		fmt.Sprintf("Database version 2 of %d (%d pending)", latest, latest-2),
+	)
 }
 
 func TestMigrateDown(t *testing.T) {
@@ -130,8 +140,11 @@ func TestMigrateDown(t *testing.T) {
 		_, err := run(t, "", args...)
 		cmdtest.ErrContains(t, err, "pass the --yes flag")
 	}
-	cmdtest.Contains(t, mustRun(t, "migrate", "status"),
-		fmt.Sprintf("Database version %d of %d", latest-1, latest))
+	cmdtest.Contains(
+		t,
+		mustRun(t, "migrate", "status"),
+		fmt.Sprintf("Database version %d of %d", latest-1, latest),
+	)
 
 	out = mustRun(t, "migrate", "down", "--steps", "0", "--yes")
 	cmdtest.Contains(t, out, "Database cleared")