chore(docs): convert parser_test.go + search_bench_test.go + add countSubstring helper

Drops `fmt` + `strings` imports from both test files.

Conversions in parser_test.go:
- strings.TrimSpace → Trim (1 site)
- strings.Builder → Builder (1 site)
- strings.Count → countSubstring() local helper (1 site; no core
  wrapper exists in dappco.re/go for strings.Count)
- fmt.Sprintf → Sprintf (5 sites)

Conversions in search_bench_test.go:
- strings.ToUpper → Upper (1 site)
- fmt.Sprintf → Sprintf (8 sites)

Adds countSubstring() helper to parser.go's package-local helper
section. Will be replaced by core.Count when the dappco.re/go bump
lands as a published tag.

All docs tests pass (and benchmarks compile).

Banned-imports: 13 → 9 (-4) for docs.

Refs Mantis #1316

Filed-by: hephaestus
Co-authored-by: Hephaestus <hephaestus@lthn.ai>

go/pkg/help/parser.go

@@ -10,6 +10,25 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
+// countSubstring returns the number of non-overlapping occurrences of substr
+// in s. Equivalent of strings.Count without importing strings; no core
+// wrapper exists in dappco.re/go.
+func countSubstring(s, substr string) int {
+	if substr == "" {
+		return len(s) + 1
+	}
+	count := 0
+	start := 0
+	for {
+		idx := core.Index(s[start:], substr)
+		if idx < 0 {
+			return count
+		}
+		count++
+		start += idx + len(substr)
+	}
+}
+
 // repeat returns a string consisting of n copies of s. Equivalent of
 // strings.Repeat without importing strings; no core wrapper exists in
 // dappco.re/go.

go/pkg/help/parser_test.go

@@ -3,8 +3,6 @@ package help
 
 import (
 	. "dappco.re/go"
-	"fmt"
-	"strings"
 )
 
 func TestGenerateID_Good(t *T) {
@@ -373,7 +371,7 @@ order: 99
 	AssertEqual(t, 99, topic.Order)
 	AssertEmpty(t, topic.Sections)
 	// Body after frontmatter is just a newline
-	AssertEqual(t, "", strings.TrimSpace(topic.Content))
+	AssertEqual(t, "", Trim(topic.Content))
 }
 
 func TestExtractFrontmatter_Bad_MalformedYAML(t *T) {
@@ -478,8 +476,8 @@ Deepest heading level.
 		{5, "Level 5"},
 		{6, "Level 6"},
 	} {
-		AssertEqual(t, expected.level, sections[i].Level, fmt.Sprintf("section %d level", i))
-		AssertEqual(t, expected.title, sections[i].Title, fmt.Sprintf("section %d title", i))
+		AssertEqual(t, expected.level, sections[i].Level, Sprintf("section %d level", i))
+		AssertEqual(t, expected.title, sections[i].Title, Sprintf("section %d title", i))
 	}
 
 	// Verify content is associated with correct sections
@@ -605,21 +603,21 @@ Content with Кириллица, 中文, العربية, and हिन्दी.
 
 func TestParseTopic_Good_VeryLongDocument(t *T) {
 	// Build a document with 10,000+ lines
-	var b strings.Builder
+	var b Builder
 
 	b.WriteString("---\ntitle: Massive Document\ntags: [large, stress]\n---\n\n")
 
 	// Generate 100 sections, each with ~100 lines of content
 	for i := range 100 {
-		b.WriteString(fmt.Sprintf("## Section %d\n\n", i+1))
+		b.WriteString(Sprintf("## Section %d\n\n", i+1))
 		for j := range 100 {
-			b.WriteString(fmt.Sprintf("Line %d of section %d: Lorem ipsum dolor sit amet.\n", j+1, i+1))
+			b.WriteString(Sprintf("Line %d of section %d: Lorem ipsum dolor sit amet.\n", j+1, i+1))
 		}
 		b.WriteString("\n")
 	}
 
 	content := b.String()
-	lineCount := strings.Count(content, "\n")
+	lineCount := countSubstring(content, "\n")
 	AssertGreater(t, lineCount, 10000, "document should exceed 10K lines")
 
 	topic, err := ParseTopic("massive.md", []byte(content))

go/pkg/help/search_bench_test.go

@@ -3,8 +3,6 @@ package help
 
 import (
 	. "dappco.re/go"
-	"fmt"
-	"strings"
 )
 
 // titleCase capitalises the first letter of a string.
@@ -13,7 +11,7 @@ func titleCase(s string) string {
 	if len(s) == 0 {
 		return s
 	}
-	return strings.ToUpper(s[:1]) + s[1:]
+	return Upper(s[:1]) + s[1:]
 }
 
 // buildLargeCatalog creates a search index with n topics for benchmarking.
@@ -43,8 +41,8 @@ func buildLargeCatalog(n int) *searchIndex {
 		verb := verbs[i%len(verbs)]
 		adj := adjectives[i%len(adjectives)]
 
-		title := fmt.Sprintf("%s %s Guide %d", titleCase(adj), titleCase(subj), i)
-		content := fmt.Sprintf(
+		title := Sprintf("%s %s Guide %d", titleCase(adj), titleCase(subj), i)
+		content := Sprintf(
 			"This guide covers how to %s %s %s systems. "+
 				"It includes step-by-step instructions for setting up %s "+
 				"in both development and production environments. "+
@@ -55,24 +53,24 @@ func buildLargeCatalog(n int) *searchIndex {
 
 		sections := []Section{
 			{
-				ID:      fmt.Sprintf("overview-%d", i),
+				ID:      Sprintf("overview-%d", i),
 				Title:   "Overview",
-				Content: fmt.Sprintf("An overview of %s %s patterns and best practices.", adj, subj),
+				Content: Sprintf("An overview of %s %s patterns and best practices.", adj, subj),
 			},
 			{
-				ID:      fmt.Sprintf("setup-%d", i),
-				Title:   fmt.Sprintf("%s Setup", titleCase(subj)),
-				Content: fmt.Sprintf("Detailed setup instructions for %s. Run the %s command to begin.", subj, verb),
+				ID:      Sprintf("setup-%d", i),
+				Title:   Sprintf("%s Setup", titleCase(subj)),
+				Content: Sprintf("Detailed setup instructions for %s. Run the %s command to begin.", subj, verb),
 			},
 			{
-				ID:      fmt.Sprintf("troubleshooting-%d", i),
+				ID:      Sprintf("troubleshooting-%d", i),
 				Title:   "Troubleshooting",
-				Content: fmt.Sprintf("Common issues when working with %s and how to resolve them.", subj),
+				Content: Sprintf("Common issues when working with %s and how to resolve them.", subj),
 			},
 		}
 
 		idx.Add(&Topic{
-			ID:       fmt.Sprintf("%s-%s-%d", adj, subj, i),
+			ID:       Sprintf("%s-%s-%d", adj, subj, i),
 			Title:    title,
 			Content:  content,
 			Sections: sections,