mod: Phase 3 — Re-port unmerged upstream PRs

Re-applied upstream PRs not yet merged to upstream/master:

- #1055: Byte-level framebuffer writes (fillPhysicalHSpan*,
  optimized fillRect/drawLine/fillRectDither/fillPolygon)
- #1027: Word-width cache (FNV-1a, 128-entry) and hyphenation
  early exit in ParsedText for 7-9% layout speedup
- #1068: Already present in upstream — URL hyphenation fix
- #1019: Already present in upstream — file extensions in browser
- #1090/#1185/#1217: KOReader sync improvements — binary credential
  store, document hash caching, ChapterXPathIndexer integration
- #1209: OPDS multi-server — OpdsBookBrowserActivity accepts
  OpdsServer, directory picker for downloads, download-complete
  prompt with open/back options
- #857: Dictionary activities already ported in Phase 1/2
- #1003: Placeholder cover already integrated in Phase 2

Also fixed: STR_OFF i18n string, include paths, replaced
Epub::isValidThumbnailBmp with Storage.exists, replaced
StringUtils::checkFileExtension with FsHelpers equivalents.

Made-with: Cursor

lib/Epub/Epub/hyphenation/HyphenationCommon.cpp

@@ -95,8 +95,6 @@ bool isPunctuation(const uint32_t cp) {
     case '}':
     case '[':
     case ']':
-    case '/':
-    case 0x2039:  // ‹
     case 0x203A:  // ›
     case 0x2026:  // …
       return true;
@@ -109,6 +107,7 @@ bool isAsciiDigit(const uint32_t cp) { return cp >= '0' && cp <= '9'; }
 
 bool isExplicitHyphen(const uint32_t cp) {
   switch (cp) {
+    case '/':
     case '-':
     case 0x00AD:  // soft hyphen
     case 0x058A:  // Armenian hyphen