refactor(docs): replace deprecated strings.Title with cases.Title

strings.Title has been deprecated since Go 1.18 because it does not
handle Unicode properly. Replace it with cases.Title from
golang.org/x/text which correctly handles language-specific title
casing. Applied to breadcrumb generation and document title formatting.

internal/docs/handler.go

@@ -7,13 +7,15 @@ import (
 	"os"
 	"strings"
 
+	"bookhoard/templates"
+
 	"github.com/yuin/goldmark"
 	highlighting "github.com/yuin/goldmark-highlighting"
 	"github.com/yuin/goldmark/extension"
 	"github.com/yuin/goldmark/parser"
 	"github.com/yuin/goldmark/renderer/html"
-
-	"bookhoard/templates"
+	"golang.org/x/text/cases"
+	"golang.org/x/text/language"
 )
 
 type DocsHandler struct {
@@ -169,7 +171,7 @@ func (h *DocsHandler) generateBreadcrumb(docPath string) []templates.BreadcrumbI
 		// Don't add the last part (current page)
 		if i < len(parts)-1 {
 			breadcrumb = append(breadcrumb, templates.BreadcrumbItem{
-				Title: strings.Title(strings.ReplaceAll(part, "-", " ")),
+				Title: cases.Title(language.English).String(strings.ReplaceAll(part, "-", " ")),
 				URL:   "/docs" + path,
 			})
 		}

internal/docs/navigation.go

@@ -5,6 +5,9 @@ import (
 	"strings"
 
 	"bookhoard/templates"
+
+	"golang.org/x/text/cases"
+	"golang.org/x/text/language"
 )
 
 // BuildNavigation creates the navigation structure from the docs filesystem
@@ -100,7 +103,7 @@ func (h *DocsHandler) getDocTitle(docPath string) string {
 	filename := parts[len(parts)-1]
 
 	// Convert to title case
-	title = strings.Title(strings.ReplaceAll(filename, "-", " "))
+	title = cases.Title(language.English).String(strings.ReplaceAll(filename, "-", " "))
 
 	// Handle special cases
 	switch filename {