feat(extraction): same-file value-reference edges for impact analysis — 15 languages (#897)

Adds same-file value-reference edges (reader symbol → const/var it reads) so impact analysis catches a constant's same-file consumers, closing the 'change this table, break its readers' hole. 15 languages validated S/M/L on public OSS: TS/JS/tsx, Go, Python, Rust, Ruby, C, Java, C#, PHP, Scala, Kotlin, Swift, Dart, Pascal/Delphi (+ Svelte/Vue/Astro inherited). Edges-only — node count identical on/off; default ON, CODEGRAPH_VALUE_REFS=0 opts out.

src/extraction/languages/java.ts

@@ -86,6 +86,19 @@ export const javaExtractor: LanguageExtractor = {
     }
     return false;
   },
+  // A `static final` field is a Java constant (`MAX_ITEMS`, lookup tables,
+  // shared config). Drives `constant` kind so value-reference edges target it;
+  // instance / `final`-only / `static`-only fields stay mutable `field`s.
+  isConst: (node) => {
+    for (let i = 0; i < node.childCount; i++) {
+      const child = node.child(i);
+      if (child?.type === 'modifiers') {
+        const text = child.text;
+        return /\bstatic\b/.test(text) && /\bfinal\b/.test(text);
+      }
+    }
+    return false;
+  },
   extractImport: (node, source) => {
     const importText = source.substring(node.startIndex, node.endIndex).trim();
     const scopedId = node.namedChildren.find((c: SyntaxNode) => c.type === 'scoped_identifier');