fix(reader): scale percentage correctly, add 5s init guard

- reader.templ: divide DB percentage (0-1) by 100 was wrong; actually
  the router multiplies by 100, so template now divides by 100 to get
  back to 0-1 range for foliate-js savedPercentage
- reader.ts: add 5-second initTime guard to prevent overwriting
  existing progress with initial position on page load

templates/reader.templ

@@ -14,7 +14,7 @@ func readerInitExpr(metadata ReaderMetadata, progress ReadingProgress) string {
 		"mangaType":        metadata.MangaType,
 	}
 	if progress.Percentage > 0 {
-		config["savedPercentage"] = progress.Percentage
+		config["savedPercentage"] = progress.Percentage / 100
 	}
 	if progress.EpubCfi != "" {
 		config["savedCfi"] = progress.EpubCfi

templates/reader_templ.go

@@ -22,7 +22,7 @@ func readerInitExpr(metadata ReaderMetadata, progress ReadingProgress) string {
 		"mangaType":        metadata.MangaType,
 	}
 	if progress.Percentage > 0 {
-		config["savedPercentage"] = progress.Percentage
+		config["savedPercentage"] = progress.Percentage / 100
 	}
 	if progress.EpubCfi != "" {
 		config["savedCfi"] = progress.EpubCfi

web/src/reader/reader.ts

@@ -383,6 +383,7 @@ document.addEventListener("alpine:init", () => {
     tocItems: [] as any[],
     mediaItemId: "" as string,
     saveTimeout: null as ReturnType<typeof setTimeout> | null,
+    initTime: 0 as number,
     readingTheme: "light" as string,
     readingMode: "light" as string,
     readingFont: "literata" as string,
@@ -525,9 +526,11 @@ document.addEventListener("alpine:init", () => {
       } else {
         await this.view.init({});
       }
+      this.initTime = Date.now();
       this.fetchReadingSpeed();
     },
     debouncedSaveProgress(fraction: number, location: any, cfi: string) {
+      if (Date.now() - this.initTime < 5000) return;
       if (this.saveTimeout) clearTimeout(this.saveTimeout);
       this.saveTimeout = setTimeout(() => {
         this.saveProgress(fraction, location, cfi);