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/docs/documentation.mdc

@@ -0,0 +1,37 @@
+---
+alwaysApply: false
+---
+# Directive for Documentation Generation
+
+1. Produce a **small, focused set of documents** rather than an overwhelming volume.
+2. Ensure the content is **maintainable and worth preserving**, so that humans
+   are motivated to keep it up to date.
+3. Prioritize **educational value**: the documents must clearly explain the
+   workings of the system.
+4. Avoid **shallow, generic, or filler explanations** often found in AI-generated
+   documentation.
+5. Aim for **clarity, depth, and usefulness**, so readers gain genuine understanding.
+6. Always check the local system date to determine current date.
+
+## Model Implementation Checklist
+
+### Before Documentation Creation
+
+- [ ] **Scope Definition**: Define what needs to be documented
+- [ ] **Audience Analysis**: Identify target readers and their needs
+- [ ] **Content Planning**: Plan focused, educational content structure
+- [ ] **Maintenance Planning**: Ensure content will be worth preserving
+
+### During Documentation Creation
+
+- [ ] **Educational Focus**: Clearly explain how the system works
+- [ ] **Depth and Clarity**: Provide genuine understanding, not surface explanations
+- [ ] **Focused Content**: Keep documents small and focused on specific topics
+- [ ] **Current Date**: Check local system date for time-sensitive content
+
+### After Documentation Creation
+
+- [ ] **Quality Review**: Ensure content is clear, deep, and useful
+- [ ] **Maintainability Check**: Verify content motivates humans to keep it updated
+- [ ] **Audience Validation**: Confirm content meets target reader needs
+- [ ] **Integration**: Integrate with existing documentation structure