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/GfxRenderer/GfxRenderer.h

@@ -45,6 +45,14 @@ class GfxRenderer {
   void drawPixelDither(int x, int y) const;
   template <Color color>
   void fillArc(int maxRadius, int cx, int cy, int xDir, int yDir) const;
+  // Write a patterned horizontal span directly to the physical framebuffer using byte-level operations.
+  // phyY: physical row; phyX_start/phyX_end: inclusive physical column range.
+  // patternByte is repeated across the span; partial edge bytes are blended with existing content.
+  // Bit layout: MSB-first (bit 7 = phyX=0); 0 bits = dark pixel, 1 bits = white pixel.
+  void fillPhysicalHSpanByte(int phyY, int phyX_start, int phyX_end, uint8_t patternByte) const;
+  // Write a solid horizontal span directly to the physical framebuffer using byte-level operations.
+  // Thin wrapper around fillPhysicalHSpanByte: state=true → 0x00 (dark), false → 0xFF (white).
+  void fillPhysicalHSpan(int phyY, int phyX_start, int phyX_end, bool state) const;
 
  public:
   explicit GfxRenderer(HalDisplay& halDisplay)