fix(dictionary): comprehensive dictionary fixes for stability and UX

This commit completes a series of fixes addressing dictionary crashes,
memory issues, and UI/UX improvements.

Memory & Stability (from previous checkpoints):
- Add uncompressed dictionary (.dict) support to avoid decompression
  memory issues with large dictzip chunks (58KB -> direct read)
- Implement chunked on-demand HTML parsing for large definitions,
  parsing pages as user navigates rather than all at once
- Refactor TextBlock/ParsedText from std::list to std::vector,
  reducing heap allocations by ~12x per TextBlock and eliminating
  crashes from repeated page navigation due to heap fragmentation
- Limit cached pages to MAX_CACHED_PAGES (4) with re-parse capability
  for backward navigation beyond the cache window

UI/Layout Fixes (this commit):
- Restore DictionaryMargins.h for proper orientation-aware button
  hint space (front buttons: 45px, side buttons: 50px)
- Add side button hints to definition screen with proper "<" / ">"
  labels for page navigation
- Add side button hints to word selection screen ("UP"/"DOWN" labels,
  borderless, small font, 2px edge margin)
- Add side button hints to dictionary menu ("< Prev", "Next >")
- Fix double-button press bug when loading new chunks by checking
  forward navigation availability after parsing instead of page count
- Add drawSideButtonHints() drawBorder parameter for minimal hints
- Add drawTextRotated90CCW() for LandscapeCCW text orientation
- Move page indicator up to avoid bezel cutoff

src/activities/dictionary/DictionarySearchActivity.cpp

@@ -235,14 +235,14 @@ void DictionarySearchActivity::displayTaskLoop() {
 void DictionarySearchActivity::render() const {
   renderer.clearScreen();
 
-  // Get margins using same pattern as reader + button hint space
+  // Get margins with button hint space for all orientations
   int marginTop, marginRight, marginBottom, marginLeft;
   getDictionaryContentMargins(renderer, &marginTop, &marginRight, &marginBottom, &marginLeft);
 
   const auto pageHeight = renderer.getScreenHeight();
 
-  // Draw header with top margin
-  renderer.drawCenteredText(UI_12_FONT_ID, marginTop + 15, "Dictionary", true, EpdFontFamily::BOLD);
+  // Draw header
+  renderer.drawCenteredText(UI_12_FONT_ID, marginTop + 5, "Dictionary", true, EpdFontFamily::BOLD);
 
   if (isSearching) {
     // Show searching status with word and animated ellipsis