perf: use double instead of float for edge weights

The edge weight field was stored as float but every algorithm
(Dijkstra, Louvain, ForceDirected, PageRank, etc.) operates on
doubles internally. This caused implicit float-to-double widening
on every getWeight() call in hot loops.

Changes:
- edge.java: weight field float -> double, getter/setter updated
- GraphFileParser: Float.parseFloat -> Double.parseDouble for
  precision and to avoid widening on store
- All existing float literal callers auto-widen safely (no source
  changes needed)

Author: sauravbhattacharya001

Gvisual/src/gvisual/GraphFileParser.java

@@ -136,15 +136,15 @@ public static ParseResult parse(String filePath, Predicate<String> visibleFilter
                         continue;
                     }
 
-                    float weight;
+                    double weight;
                     try {
-                        weight = Float.parseFloat(parts[3]);
+                        weight = Double.parseDouble(parts[3]);
                     } catch (NumberFormatException e) {
                         LOGGER.warning("Skipping edge with invalid weight: " + line);
                         skipped++;
                         continue;
                     }
-                    if (Float.isNaN(weight) || Float.isInfinite(weight)) {
+                    if (Double.isNaN(weight) || Double.isInfinite(weight)) {
                         LOGGER.warning("Skipping edge with non-finite weight: " + line);
                         skipped++;
                         continue;

Gvisual/src/gvisual/edge.java

@@ -12,7 +12,7 @@ public class edge {
     private String edgeType;
     private String vertex1;
     private String vertex2;
-    private float weight;
+    private double weight;
     private String label;
     private Long timestamp;       // epoch millis (null = static/untimed edge)
     private Long endTimestamp;     // optional: for interval-based edges
@@ -63,12 +63,12 @@ public edge(String edgeType,String vertex1,String vertex2)
         this.vertex2 = vertex2;
     }
 
-    public void setWeight(float weight)
+    public void setWeight(double weight)
     {
         this.weight = weight;
     }
 
-    public float getWeight()
+    public double getWeight()
     {
         return this.weight;
     }