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>

data-engineering/PORTFOLIO_ORIGIN.md

@@ -0,0 +1,15 @@
+# My-Data-Engineering-Portifolio
+
+This repository has a few projects devolped during Udacity Nano-degree.
+
+Into each folder you will find more detailed infomations and the tools used.
+
+1. Data Modeling
+    1. Using Apache Cassandra
+    2. Using Postgres
+2. Cloud Data Warehouse
+3. Cloud Data Lakes using Spark
+4. Automate Pipelines using Airflow
+5. Capstone Project
+
+[Show Credentials:](https://graduation.udacity.com/confirm/43TR6CQZ)