feat(epub-reader): improve chapter resolution and progress slider UX

[AlexAndBear]

Description

This PR improves the EPUB reader with multiple enhancements:

Chapter Resolution

• Fixed multi-chapter resolution bug: EPUBs with multiple chapters in the same file (e.g., Moby Dick with 15 chapters in one .xhtml file) now correctly highlight the active chapter using DOM position comparison
• Added fallback strategy using compareDocumentPosition() for accurate chapter detection

Progress Slider UX

• Live seek while dragging: Slider now updates reading position in real-time during drag for more direct interaction

Code Quality & Stability

• Type safety: Removed all as any type casts, added proper TypeScript definitions for epubjs
• Props handling: Use destructuring instead of props.x pattern for cleaner code
• Translations: Components handle their own translatable labels instead of receiving them as props
• Null safety: Added comprehensive null checks for rendition access throughout
• Race conditions: Fixed cleanup issues in text search and component destruction
• Resource management: Proper cleanup on unmount to prevent memory leaks

Related Issue

• Fixes N/A

How Has This Been Tested?

• test environment: local macOS dev environment
• test case 1: pnpm test:unit --run packages/web-app-epub-reader (all 50 tests passing)
• test case 2: pnpm check:all (types, lint, format, tests)
• test case 3: manually test with complex EPUBs (Moby Dick) - chapter highlighting works correctly
• test case 4: manually drag progress slider - real-time seeking works smoothly

Types of changes

• Bugfix (chapter resolution for multi-chapter files)
• Enhancement (live slider seek, type safety improvements)
• Breaking change (a modification that affects current functionality)
• Technical debt (code cleanup, proper TypeScript definitions)
• Tests (updated tests for new slider behavior)
• Documentation (updates or additions to documentation)
• Maintenance (like dependency updates or tooling adjustments)