fix(pascal): attribute a free routine's calls to it, not the file (#795)

A Pascal/Delphi procedure or function defined ONLY in the implementation section
(no interface declaration, not a class method) had no node of its own, so
extractPascalDefProc's caller lookup fell through to the nodeStack top — the file
node. Every call in such a routine's body was lumped under the unit: callers
returned the file, and impact couldn't attribute the call to the routine. (Methods
were fine — they get a node from their class declaration.)

Fix: when extractPascalDefProc finds no existing node for a FREE routine (a name
with no `.`), create a function node for it and attribute the body's calls to it.
Interface-declared free routines already have a node (found via the methodIndex),
so there's no duplicate; methods keep their existing class-declaration node.

PascalCoin A/B: +511 / -145 — the +511 are calls now correctly attributed to their
actual routine (`allocate_new_datablock -> TDisposables::GetMem`), replacing -145
file-level aggregates; +248 new function nodes for the implementation-only
routines. New synthetic test asserts a free routine's call attributes to it
alongside a method caller. EXTRACTION_VERSION 17->18. Full suite green.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/extraction/extraction-version.ts

@@ -21,4 +21,4 @@
  * turns the re-index hint into noise — keep it honest (see CLAUDE.md, "Honesty
  * in the product is load-bearing").
  */
-export const EXTRACTION_VERSION = 17;
+export const EXTRACTION_VERSION = 18;

src/extraction/tree-sitter.ts

@@ -4281,10 +4281,30 @@ export class TreeSitterExtractor {
       }
     }
 
-    const parentId =
+    let parentId =
       this.methodIndex.get(fullNameKey) ||
-      this.methodIndex.get(shortNameKey) ||
-      this.nodeStack[this.nodeStack.length - 1];
+      this.methodIndex.get(shortNameKey);
+
+    // No existing node? This is an implementation-only **free** procedure/function
+    // (`procedure Helper; begin … end;` with no interface declaration and not a
+    // class method). Create a function node so its body's calls attribute to it,
+    // not to the enclosing file/module. A method (`TClass.Method`, a dotted name)
+    // always has a node from its class declaration, so this only fires for free
+    // routines — and the methodIndex lookup above already covers interface-declared
+    // free routines, so there's no duplicate.
+    if (!parentId && !fullName.includes('.')) {
+      const fnNode = this.createNode('function', fullName, declProc, {
+        signature: this.extractor?.getSignature?.(declProc, this.source),
+        visibility: this.extractor?.getVisibility?.(declProc),
+      });
+      if (fnNode) {
+        parentId = fnNode.id;
+        this.methodIndex.set(fullNameKey, fnNode.id);
+        if (!this.methodIndex.has(shortNameKey)) this.methodIndex.set(shortNameKey, fnNode.id);
+      }
+    }
+
+    if (!parentId) parentId = this.nodeStack[this.nodeStack.length - 1];
     if (!parentId) return;
 
     // Visit the block for calls