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/01-postgres-modeling/create_tables.py

@@ -0,0 +1,70 @@
+import psycopg2
+from sql_queries import create_table_queries, drop_table_queries
+
+
+def create_database():
+    """
+    - Creates and connects to the sparkifydb
+    - Returns the connection and cursor to sparkifydb
+    """
+    
+    # connect to default database
+    conn = psycopg2.connect("host=127.0.0.1 dbname=studentdb user=student password=student")
+    conn.set_session(autocommit=True)
+    cur = conn.cursor()
+    
+    # create sparkify database with UTF8 encoding
+    cur.execute("DROP DATABASE IF EXISTS sparkifydb")
+    cur.execute("CREATE DATABASE sparkifydb WITH ENCODING 'utf8' TEMPLATE template0")
+
+    # close connection to default database
+    conn.close()    
+    
+    # connect to sparkify database
+    conn = psycopg2.connect("host=127.0.0.1 dbname=sparkifydb user=student password=student")
+    cur = conn.cursor()
+    
+    return cur, conn
+
+
+def drop_tables(cur, conn):
+    """
+    Drops each table using the queries in `drop_table_queries` list.
+    """
+    for query in drop_table_queries:
+        cur.execute(query)
+        conn.commit()
+
+
+def create_tables(cur, conn):
+    """
+    Creates each table using the queries in `create_table_queries` list. 
+    """
+    for query in create_table_queries:
+        cur.execute(query)
+        conn.commit()
+
+
+def main():
+    """
+    - Drops (if exists) and Creates the sparkify database. 
+    
+    - Establishes connection with the sparkify database and gets
+    cursor to it.  
+    
+    - Drops all the tables.  
+    
+    - Creates all tables needed. 
+    
+    - Finally, closes the connection. 
+    """
+    cur, conn = create_database()
+    
+    drop_tables(cur, conn)
+    create_tables(cur, conn)
+
+    conn.close()
+
+
+if __name__ == "__main__":
+    main()