feat: Add keyboard shortcut for toggling search/filter panel and update documentation

docs/FEATURES.md

@@ -37,6 +37,7 @@ Professional keyboard shortcut system for efficient navigation and operation.
 #### Data Management:
 - **Ctrl+N**: Clear entries
 - **Ctrl+R / F5**: Refresh data
+- **Ctrl+F**: Toggle search/filter panel
 - **Delete**: Delete selected entry
 - **Escape**: Clear selection
 
@@ -177,6 +178,37 @@ Comprehensive symptom tracking with configurable pathologies.
 - **Scale-based Rating**: 0-10 rating system for symptom severity
 - **Historical Tracking**: Full symptom history with trend analysis
 
+### 🔍 Advanced Search and Filter System
+Powerful data filtering and search capabilities for analyzing your health data.
+
+#### Search Features:
+- **Text Search**: Search through notes and text fields with intelligent matching
+- **Date Range Filtering**: Filter entries by specific date ranges
+- **Medicine Filtering**: Show only entries where specific medicines were taken or not taken
+- **Pathology Score Filtering**: Filter by symptom severity score ranges
+- **Combined Filters**: Use multiple filters simultaneously for precise data analysis
+
+#### User Interface:
+- **Toggle Panel**: Access via Ctrl+F or Tools menu - panel shows/hides as needed
+- **Quick Filters**: Pre-configured filters for common use cases
+- **Search History**: Remember previous search terms for easy reuse
+- **Filter Summary**: Clear display of active filters and their effects
+- **Real-time Updates**: Results update immediately as filters are applied
+
+#### Filter Types:
+- **Date Range**: Filter entries between start and end dates (inclusive)
+- **Medicine Status**: Show entries where medicines were taken (✓) or not taken (✗)
+- **Symptom Scores**: Filter by minimum and maximum pathology scores
+- **Text Search**: Case-insensitive search through notes and text content
+- **Combined Logic**: Multiple filters work together with AND logic
+
+#### Usage Examples:
+- Find all entries where anxiety score was > 7
+- Show only days when Bupropion was taken
+- Search for entries containing "headache" in notes
+- Filter to last 30 days with depression scores between 3-6
+- Combine filters: High anxiety + specific medicine + date range
+
 ### 📝 Data Management
 Robust data handling with comprehensive backup and migration support.