feat(tags): Add --tag flag support to core commands for multi-context task management

- parse-prd now supports creating tasks in specific contexts
- Fixed tag preservation logic to prevent data loss
- analyze-complexity generates tag-specific reports
- Non-existent tags created automatically
- Enables rapid prototyping and parallel development workflows

test-prd.txt

@@ -0,0 +1,14 @@
+# Test PRD
+
+## Project Overview
+This is a simple test project to verify parse-prd functionality.
+
+## Features
+- Feature A: Basic setup
+- Feature B: Core functionality  
+- Feature C: Testing
+
+## Requirements
+- Use Node.js
+- Include basic tests
+- Simple CLI interface