Add "Verifier" for Dijkstra algorithm

[ScottBBarfuss]

From what I understand looking at the main branch, all existing algorithms in Redux have a dedicated verifier class that implements the IVerifier interface and is discovered automatically by the API through reflection.

We'll need to create a problem class that can be constructed from a string instance, then implement a DijkstraVerifier : IVerifier with a parameterless constructor and a verify(problem, certificate) method. The verifier must live in the problem’s Verifiers folder so the UI can detect it.

The verification logic will parse the certificate and check it against the graph instance. Once this class is added, the framework should automatically expose it through the /ProblemProvider/verify endpoint automatically.

[RajNilkar]

Created a DijkstraVerifier class. Might need to change the methods in there, just created default methods to avoid build errors in the ShortestPath_class.cs. However, I am still getting build errors, it's not recognizing the IVerifier interface. Need you take a look at it.

[ScottBBarfuss]

I've pushed changes to the shortestpath branch. I was able to see full functionality on my end, but go ahead and test it yourself. I also know I introduced a lot of warnings; that will be my next step unless I'm needed elsewhere.

Push Notes:

Summary: Brought NPC_SHORTESTPATH into a functional, end-to-end state.

• Parser accepts weighted-edge instances with fallback
• Implemented a working Dijkstra solver over the repo’s UtilCollectionGraph/SPADE edge representations
• Added verifier that checks both validity and optimality
• Updated the visualization to return the correct API graph JSON and optionally highlight a solution path.
• Default instance representation changed to a weighted format ({u,v}, w); existing unweighted instances are still accepted via fallback parsing.

NPC_SHORTESTPATH/SHORTESTPATH_Class.cs:

• Updated default instance for explicit weighted tuples
• Added dual parsing strategy (first attempts weighted, then unweighted)
• Edge case robustness things

NPC_SHORTESTPATH/Solvers/DijkstraPriorityQueue.cs:

• Added namespace
• Minor cleanup

NPC_SHORTESTPATH/Solvers/DijkstraSolver.cs:

• Built Dijkstra solver implementation
• Nodes are rebuilt and certificates are output
• UtilCollection edges interpreted differently based on content
• Reacts to negative weights and unreachable target

NPC_SHORTESTPATH/Verifiers/ShortestPathVerifier.cs:

• Implemented verification
• Blank is treated as "no path exists" and valid iff target unreachable
• Checks that path starts at selected source and ends at target
• Accumulates total weight and computes true shortest distance

NPC_SHORTESTPATH/Visualizations/ShortestPathVisualization.cs:

• Fixed interface alignment
• visualize(problem) returns problem.graph.ToAPIGraph()
• Added SolvedVisualization(): parses solution cert as node path then colors