refactor: restructure cursor rules with new meta-rule architecture

- Remove legacy rule files (documentation.mdc, general_development.mdc, etc.)
- Implement new meta-rule system with core, app, and feature categories
- Add meta-rule files for different workflows (bug diagnosis, feature planning, etc.)
- Create organized directory structure: core/, app/, features/, database/, etc.
- Add comprehensive README.md for rules documentation
- Establish new rule architecture with always-on and workflow-specific rules

This restructuring improves rule organization, enables better workflow management,
and provides clearer separation of concerns for different development tasks.

.cursor/rules/database/legacy_dexie.mdc

@@ -0,0 +1,62 @@
+# Legacy Dexie Database — Migration Guidelines
+
+> **Agent role**: Reference this file when working with legacy Dexie
+> database code or migration patterns.
+
+## Overview
+
+All references in the codebase to Dexie apply only to migration from
+IndexedDb to Absurd SQL. Dexie is no longer used for new development.
+
+## Migration Status
+
+- **Legacy Code**: Existing Dexie implementations being migrated
+- **Target**: Absurd SQL with IndexedDB backend
+- **Timeline**: Gradual migration as features are updated
+
+## Key Principles
+
+- **No New Dexie**: All new database operations use Absurd SQL
+- **Migration Path**: Legacy code should be migrated when updated
+- **Backward Compatibility**: Maintain existing functionality during
+  migration
+
+## Integration Points
+
+- Apply these rules when updating database-related code
+- Use during feature development and refactoring
+- Include in database architecture decisions
+
+---
+
+**Status**: Legacy migration guidelines
+**Priority**: Low
+**Estimated Effort**: Ongoing reference
+**Dependencies**: absurd-sql.mdc
+**Stakeholders**: Database team, Development team
+
+All references in the codebase to Dexie apply only to migration from IndexedDb
+to Sqlite and will be deprecated in future versions.
+
+## Model Implementation Checklist
+
+### Before Legacy Dexie Work
+
+- [ ] **Migration Analysis**: Identify legacy Dexie code that needs migration
+- [ ] **Target Planning**: Plan migration to Absurd SQL with IndexedDB backend
+- [ ] **Backward Compatibility**: Plan to maintain existing functionality
+- [ ] **Testing Strategy**: Plan testing approach for migration
+
+### During Legacy Dexie Migration
+
+- [ ] **No New Dexie**: Ensure no new Dexie code is introduced
+- [ ] **Migration Implementation**: Implement migration to Absurd SQL
+- [ ] **Functionality Preservation**: Maintain existing functionality during migration
+- [ ] **Error Handling**: Implement proper error handling for migration
+
+### After Legacy Dexie Migration
+
+- [ ] **Functionality Testing**: Verify all functionality still works correctly
+- [ ] **Performance Validation**: Ensure performance meets or exceeds legacy
+- [ ] **Documentation Update**: Update database documentation
+- [ ] **Legacy Cleanup**: Remove deprecated Dexie code