chore: Update .gitignore and remove obsolete markdown files for TinyBrain

- Added entries to .gitignore for temporary migration and assessment files to streamline the project structure.
- Deleted outdated markdown files including CLEANUP_SUMMARY.md, COMPLETION_SUMMARY.md, FINAL_STATUS.md, MIGRATION.md, REAL_USAGE_TEST_RESULTS.md, TESTING_SUMMARY.md, and verify_installation.py that are no longer relevant to the current architecture.
- This cleanup enhances codebase maintainability and aligns with ongoing efforts to refine TinyBrain's structure and focus on the latest integration strategies.

Author: rainmana

.gitignore

@@ -61,3 +61,12 @@ Thumbs.db
 
 # UV
 .uv/
+
+# Temporary migration/assessment files
+*_ASSESSMENT.md
+*_SUMMARY.md
+*_STATUS.md
+*_RESULTS.md
+MIGRATION.md
+verify_installation.py
+test_real_usage.py