[UPDATE ALGORITHM] Complete Breadth-First Search (BFS) implementation #4751

Description:

The repository already has a dedicated BFS directory and documentation, but the implementation file is currently empty:

• Graph Algorithms/Breadth-First Search (BFS)/Program.c (0 bytes)

The README.md in the same folder explains BFS and expected logic, but there is no runnable C implementation.
I want to update this by adding a complete BFS program (queue + visited array) for graph traversal from a source node.

Checklist:

• Contributor in GSSoC-ext
• Want to work on it

Affected Algorithm:

Breadth-First Search (BFS)
Directory: Graph Algorithms/Breadth-First Search (BFS)/

Additional Information:

Planned update includes:

• Full Program.c implementation for BFS traversal
• Sample graph in main() to demonstrate output
• Keep README and code behavior aligned

Please assign this issue to me.