chore(algorithms): remove package (moved to graphbox)

The algorithms package has been migrated to the graphbox repository
for focused graph algorithm development and experimentation.

Removed:
- Graph clustering algorithms (Louvain, Leiden, label propagation, Infomap)
- Graph analysis (connected components, SCC, cycle detection, topological sort)
- Decomposition algorithms (k-core, biconnected components, core-periphery)
- Extraction utilities (ego networks, path finding, motif detection, k-truss)
- Pathfinding algorithms (Dijkstra, path ranking, mutual information)
- Graph traversal (BFS, DFS)
- Metrics (modularity, conductance, cluster quality)
- Partitioning (spectral clustering)

Author: Mearman