Epub reader themes (#97)

* Implemented a custom theme engine for the EPUB reader, allowing users to switch between built-in themes (System, Light, Dark, Sepia, Slate, and OLED).

Key changes include:
- Added `ReaderThemePanel` and theme selection logic to `EpubReaderScreen`.
- Introduced a theme persistence layer using SharedPreferences.
- Updated `ChapterWebView` and `epub_reader.js` to dynamically apply background and text colors via JavaScript, including improved contrast adjustment for inline styles.
- Enhanced `CssParser` and `ContentStyler` in the paginated reader to adapt CSS colors based on the active theme's background and text luminance.
- Integrated theme-specific background and text colors into `PaginatedReaderScreen` and its layout components.
- Added a theme palette icon to the reader controls.

* Added custom theme builder and texture support to EPUB reader

* Refactored color picker(PDF) into shared components and enhanced EPUB theme editor

* Updated theme customization UI and improved WebView theme application efficiency

* Updated page flip animation to use paper color with a theme-based tint

* Improved state restoration during paginated reader reconfiguration

app/src/main/java/com/aryan/reader/paginatedreader/ContentStyler.kt

@@ -50,6 +50,8 @@ class ContentStyler(
     private val fontFamilyMap: Map<String, FontFamily>,
     private val density: Density,
     private val isDarkTheme: Boolean,
+    private val themeBackgroundColor: Color,
+    private val themeTextColor: Color,
     private val chapterAbsPath: String,
     private val extractionBasePath: String,
     private val userTextAlign: TextAlign?
@@ -59,7 +61,6 @@ class ContentStyler(
         return groupFloatingBlocks(semanticBlocks.mapNotNull { styleBlock(it) })
     }
 
-    // ADD this function to group floating blocks, similar to the original parser
     private fun groupFloatingBlocks(blocks: List<ContentBlock>): List<ContentBlock> {
         if (blocks.isEmpty()) return emptyList()
 
@@ -71,7 +72,6 @@ class ContentStyler(
             val floatDirection = (currentBlock as? ImageBlock)?.style?.float
 
             if (currentBlock is ImageBlock && floatDirection in listOf("left", "right")) {
-                val floatedImage = currentBlock
                 val paragraphsToWrap = mutableListOf<ParagraphBlock>()
 
                 while (processingQueue.isNotEmpty()) {
@@ -86,11 +86,11 @@ class ContentStyler(
                     }
                 }
                 val wrappingBlock = WrappingContentBlock(
-                    floatedImage,
+                    currentBlock,
                     paragraphsToWrap,
-                    elementId = floatedImage.elementId,
-                    cfi = floatedImage.cfi,
-                    blockIndex = floatedImage.blockIndex
+                    elementId = currentBlock.elementId,
+                    cfi = currentBlock.cfi,
+                    blockIndex = currentBlock.blockIndex
                 )
                 result.add(wrappingBlock)
             } else {
@@ -208,7 +208,7 @@ class ContentStyler(
     private fun applyThemeToStyle(style: CssStyle): CssStyle {
         val newSpanStyle = style.spanStyle.let { original ->
             val newColor = if (original.color.isSpecified) {
-                CssParser.adaptColorForTheme(original.color, isDarkTheme, isBackground = false)
+                CssParser.adaptColorForTheme(original.color, isDarkTheme, isBackground = false, themeBackgroundColor, themeTextColor)
             } else {
                 original.color
             }
@@ -217,14 +217,14 @@ class ContentStyler(
 
         val newBlockStyle = style.blockStyle.let { original ->
             val newBgColor = if (original.backgroundColor.isSpecified) {
-                CssParser.adaptColorForTheme(original.backgroundColor, isDarkTheme, isBackground = true)
+                CssParser.adaptColorForTheme(original.backgroundColor, isDarkTheme, isBackground = true, themeBackgroundColor, themeTextColor)
             } else {
                 original.backgroundColor
             }
 
             fun themeBorder(b: BorderStyle?): BorderStyle? {
                 if (b == null) return null
-                val newColor = CssParser.adaptColorForTheme(b.color, isDarkTheme, isBackground = false)
+                val newColor = CssParser.adaptColorForTheme(b.color, isDarkTheme, isBackground = false, themeBackgroundColor, themeTextColor)
                 return b.copy(color = newColor)
             }
 
@@ -474,7 +474,7 @@ class ContentStyler(
     }
 
     private fun toRoman(number: Int): String {
-        if (number < 1 || number > 3999) return number.toString()
+        if (number !in 1..3999) return number.toString()
         val values = listOf(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1)
         val symbols = listOf("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I")
         val result = StringBuilder()