feat(viewer): add PrintMode for browser print/PDF export

Adds RenderOptions.PrintMode flag. When true:
- view.js (table filters) is not loaded
- window.print() fires on page load
- @media print CSS hides filters, collapses grid to single column,
  adds page-break hints for section cards

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

viewer/render.go

@@ -86,6 +86,7 @@ type RenderOptions struct {
 	DownloadArchiveLabel string
 	NoticeTitle          string
 	NoticeBody           string
+	PrintMode            bool
 }
 
 func RenderHTML(snapshot []byte, title string) ([]byte, error) {
@@ -103,6 +104,7 @@ func RenderHTMLWithOptions(snapshot []byte, title string, opts RenderOptions) ([
 func buildPageData(snapshot []byte, title string, opts RenderOptions) (pageData, error) {
 	page := pageData{
 		Title:                title,
+		PrintMode:            opts.PrintMode,
 		NoticeTitle:          strings.TrimSpace(opts.NoticeTitle),
 		NoticeBody:           strings.TrimSpace(opts.NoticeBody),
 		DownloadArchiveURL:   strings.TrimSpace(opts.DownloadArchiveURL),