UI Improvements: Document Date Display & Accordion Toggle Controls

[Jorge5452]

UI Improvements: Document Date Display & Accordion Toggle Controls

Summary

This PR enhances the chat interface by fixing document date extraction and adding expand/collapse controls for source accordions.

Changes

Date Extraction & Display

• Added extract_date_from_title() utility to parse dates from document titles (DDMMAAAA format)
• Implemented age calculation with visual indicators:
  • 🟢 Very recent (< 30 days)
  • 🟡 Recent (< 90 days)
  • 🟠 This year (< 365 days)
  • 🔴 Older documents (years)
• Enhanced _create_document_sources() in RAG service to extract and pass date information

Accordion UX Improvements

• Added "Expand ↓ / Collapse ↑" toggle button for managing all source accordions simultaneously
• Implemented expand/collapse functionality for:
  • Main sources accordion
  • Individual document details
  • Nested chunk/fragment details
• Enhanced visual feedback with "Ver más ↓" / "Ver menos ↑" indicators on collapsible sections
• Positioned toggle button in top-right corner for better accessibility

Files Modified

Backend

• rag_service.py: Integrated extract_date_from_title() in document source creation pipeline
• utils/date_utils.py: New date parsing and formatting utilities with Spanish locale support
• utils/context_renderer.py: Updated _get_age_text() to render age metadata with emoji indicators

Frontend

• static/css/chat.css: Toggle button styling and accordion container enhancements
• static/css/context.css: Refined chunk/document summary styles with chevron indicators
• static/js/chat.js: Event delegation for toggle-all functionality with state management