refactor(compose): Optimize cycle detection in DAG validation

[SyedaAnshrahGillani]

This pull request optimizes the cycle detection algorithm in the validateDAG
function by replacing the existing implementation with a more efficient
depth-first search (DFS) based approach.

Previously, the function used a map to store the in-degree of each node and
then iteratively removed nodes with an in-degree of 0. This approach has a
time complexity of O(V + E), where V is the number of vertices and E is the
number of edges. The new implementation uses a DFS-based approach, which is
generally faster in practice while having the same time complexity.

Changes:

• compose/graph.go: Replaced the existing validateDAG function with a more
  efficient implementation that uses a depth-first search (DFS) to detect
  cycles.

This optimization improves the performance of the graph compilation process,
especially for large and complex graphs.