docs(jdbc): add conceptual diagrams to illustrate JDBC internals and workflow

What
- Added visual resources under Section28JDBCusingSQLite/JDBC to complement textual explanations:
  1. **WorkingOfJDBC.png** → shows end-to-end flow of how Java interacts with a database using JDBC.
  2. **Components of JDBC.jpeg** → highlights DriverManager, Connection, Statement, and ResultSet with their roles.
  3. **Database Programs.png** → visualizes different JDBC-based programs and their execution paths.
  4. **JDBC Drivers.png** → depicts all four JDBC driver types (Type-1 to Type-4) and their architectures.

Why
- Diagrams provide an **intuitive understanding** of JDBC beyond code samples.
- Reinforces mental models of:
  - How drivers translate between Java and database protocols.
  - How JDBC components fit together in the query lifecycle.
  - Why different driver types exist and when to use each.
- Helps learners **quickly grasp abstract concepts** with visual representation.

How
- Collected and organized key conceptual images in the JDBC package.
- Each diagram mapped to specific theoretical sections:
  - *WorkingOfJDBC.png* → aligns with "How Java talks to a database".
  - *Components of JDBC.jpeg* → supports explanation of Driver, Connection, Statement, ResultSet.
  - *Database Programs.png* → illustrates practical JDBC application usage.
  - *JDBC Drivers.png* → complements deep dive into driver types.

Key Points
- Visuals are used alongside:
  - Textual deep dives (Statement vs PreparedStatement vs CallableStatement).
  - Explanations of JDBC driver types (Type-1 to Type-4).
  - Practical database program examples with SQLite.
- Ensures both **theory + visuals** are available for stronger learning outcomes.

Real-life Applications
- Training materials for students new to JDBC.
- Documentation for internal teams working with JDBC-based applications.
- Quick reference guides for understanding driver selection and JDBC flow.

Notes
- Keep diagrams in sync with the latest code examples and documentation.
- Consider extending with UML-style diagrams for advanced JDBC concepts (connection pooling, transaction handling).

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

Author: Someshdiwan