chore(sqlite-db): add SQLite database files for JDBC demos

What
- Added two SQLite database files:
  - test.db → lightweight database for experimenting with JDBC queries.
  - univ.db → main demo database with schema (dept, students) for Section28 JDBC examples.

Why
- Required for running JDBC code samples across the project.
- Provides a consistent schema to demonstrate JDBC concepts like
  Statement, PreparedStatement, ResultSet, and CRUD operations.
- Eliminates need for an external RDBMS, ensuring out-of-the-box demos.

How
- Both .db files are created and stored locally within the project.
- Accessible using org.sqlite.JDBC driver with a JDBC URL, e.g.:
  Connection con = DriverManager.getConnection(
      "jdbc:sqlite:/Users/somesh/Java SE/JavaEvolution-Learning-Growing-Mastering/Section28JDBCusingSQLite/univ.db"
  );

Usage
- test.db → sandbox for quick SQL experiments and JDBC API practice.
- univ.db → university-style schema for relational queries and CRUD examples.

Notes
- SQLite databases are file-based and portable.
- No separate server or configuration required; works directly with JDBC driver.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan