feat(server): add owner-tools injection and inline code theme CSS

- Add owner-tools serving and injection for blog owners
- Inline code theme CSS in templates for soft reload support
- Update import paths from github.com/writekitapp to writekit
- Add optional session middleware for owner detection
- Update platform index with improved UI

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/server/build.go

@@ -8,9 +8,9 @@ import (
 	"sync"
 	"time"
 
-	"github.com/writekitapp/writekit/internal/build/templates"
-	"github.com/writekitapp/writekit/internal/markdown"
-	"github.com/writekitapp/writekit/internal/tenant"
+	"writekit/internal/tenant/templates"
+	"writekit/internal/markdown"
+	"writekit/internal/tenant"
 )
 
 type renderedPage struct {
@@ -39,14 +39,16 @@ func (s *Server) rebuildSite(ctx context.Context, tenantID string, db *sql.DB, h
 	codeTheme := getSettingOr(settings, "code_theme", "github")
 	fontKey := getSettingOr(settings, "font", "system")
 	isDemo := getSettingOr(settings, "is_demo", "") == "true"
+	codeThemeCSS, _ := markdown.GenerateChromaCSS(codeTheme)
 
 	pageData := templates.PageData{
-		SiteName:   siteName,
-		Year:       time.Now().Year(),
-		FontURL:    templates.GetFontURL(fontKey),
-		FontFamily: templates.GetFontFamily(fontKey),
-		Settings:   settingsToMap(settings),
-		NoIndex:    isDemo,
+		SiteName:     siteName,
+		Year:         time.Now().Year(),
+		FontURL:      templates.GetFontURL(fontKey),
+		FontFamily:   templates.GetFontFamily(fontKey),
+		Settings:     settingsToMap(settings),
+		NoIndex:      isDemo,
+		CodeThemeCSS: template.CSS(codeThemeCSS),
 	}
 
 	var pages []renderedPage