Remove all RDEPUBBackgroundTrace.log and bare print diagnostic calls

Keep only the evaluateFullPageMapTakeover: fullReplace diagnostic log
in RDEPUBPageMapReconciliationCoordinator.swift for future debugging.

Simplified RDEPUBBackgroundTrace to just the log method (removed measure
and debug gating). Removed all [EPUB][...], [ReadViewDemo], and
[EPUB][Pagination] print statements across the project.

Also includes earlier bug fixes:
- Fix stale currentPageNumber in extendPartial commit
- Fix pageCurl rebindVisiblePage during transition
- Fix keepCurrentWindow not removing pending update from queue
- Fix right-aligned text (巫鸿 bug) via avoidPageBreakInside,
  tail merger, and continuation paragraph normalization
- Add text-indent reset for aligned blocks in CSS compatibility layer

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

Sources/RDReaderView/EPUBUI/RDEPUBReaderController+LocationResolution.swift

@@ -94,6 +94,35 @@ extension RDEPUBReaderController {
         return location
     }
 
+    func currentVisibleRangeInfo() -> String? {
+        guard let pageNumber = currentPageNumber else {
+            return nil
+        }
+
+        if let resolvedPage = resolvedRuntimePage(forPageNumber: pageNumber) {
+            let startOffset = resolvedPage.page.pageStartOffset
+            let endOffset = max(startOffset + 1, resolvedPage.page.pageEndOffset + 1)
+            return RDEPUBTextOffsetRangeInfo(
+                href: resolvedPage.chapter.href,
+                start: startOffset,
+                end: endOffset
+            ).jsonString()
+        }
+
+        guard let textBook,
+              let page = textBook.page(at: pageNumber) else {
+            return nil
+        }
+
+        let startOffset = page.pageStartOffset
+        let endOffset = max(startOffset + 1, page.pageEndOffset + 1)
+        return RDEPUBTextOffsetRangeInfo(
+            href: page.href,
+            start: startOffset,
+            end: endOffset
+        ).jsonString()
+    }
+
     func synchronizeTextReadingState(pageNumber: Int, location: RDEPUBLocation) {
         if let resolvedPage = resolvedRuntimePage(forPageNumber: pageNumber) {
             readingSession?.updateReadingContext(