refactor: restructure monorepo for clean portfolio layout

- Move timesfm-forecast into apps/ directory
- Flatten Udacity portfolio projects from deep URL-encoded paths
  into data-engineering/01-XX numbered directories
- Remove old My-Data-Engineering-Portifolio/ parent directory
- Rewrite root README.md: professional overview with badges,
  project table, and repo structure diagram
- Create data-engineering/README.md with per-project descriptions
- Add README.md for 02-cassandra-modeling (was missing)
- Add README.md for 05-airflow-pipelines (was missing)
- Normalize capstone readme.md -> README.md
- Update .gitignore: add *.cfg, *.env, *.zip, *.sas7bdat,
  Jupyter checkpoints, IDE dirs; remove uv.lock exclusion
- Add dwh.cfg.example and dl.cfg.example credential templates
- Untrack real credential files (dwh.cfg, dl.cfg)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

apps/timesfm-forecast/.gitignore

@@ -0,0 +1,23 @@
+
+# Python
+__pycache__/
+*.py[cod]
+*.egg-info/
+*.egg
+*.pyo
+*.pyd
+
+# Environments
+.venv/
+.uv/
+
+# Streamlit
+.streamlit/
+**/.streamlit/
+
+# OS
+.DS_Store
+
+# Editors
+.vscode/
+.idea/