refactor: Make tddai framework project-agnostic and fix test configuration

FRAMEWORK DECOUPLING:
- Remove all MarkiTect-specific references from tddai core modules
- Update tddai-assistant.md to use generic examples and language
- Change CLI output from "MarkiTect Issues" to "Project Issues"
- Update coverage_analyzer.py docstring to be project-neutral

CONFIGURATION SYSTEM:
- Make tddai configuration flexible via environment variables
- Add comprehensive documentation for project setup in config.py
- Create .env.tddai and tddai-setup.sh for MarkiTect-specific config
- Support configurable workspace naming (.tddai_workspace default)

TEST INFRASTRUCTURE CLEANUP:
- Fix IssueWriter test failures caused by config validation changes
- Implement _get_test_config() helper for isolated test configurations
- Ensure all 13 IssueWriter tests pass with proper test patterns
- Maintain clean test separation and project independence

FRAMEWORK PORTABILITY:
- TDD8 methodology now completely generic and reusable
- Configuration examples for GitHub/GitLab integration
- Ready for extraction to separate repository when needed
- All 45 tests pass cleanly confirming successful refactoring

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

tddai_cli.py

@@ -189,7 +189,7 @@ def list_issues():
     """List all issues."""
     try:
         fetcher = IssueFetcher()
-        print("📋 MarkiTect Issues")
+        print("📋 Project Issues")
         print("==================")
         print()
 
@@ -220,7 +220,7 @@ def list_open_issues():
     """List only open issues."""
     try:
         fetcher = IssueFetcher()
-        print("📋 Open MarkiTect Issues (Active Backlog)")
+        print("📋 Open Project Issues (Active Backlog)")
         print("========================================")
         print()