fix: promote cross-file call edges to EXTRACTED when import evidence exists

The cross-file call resolver in `extract()` unconditionally marked every
resolved call edge as INFERRED with confidence_score 0.8 — even when the
caller's file had an explicit `imports` (symbol) or `imports_from`
(module) edge to the callee. The new CJS require handler made this gap
visible: imports were correctly EXTRACTED but the call edges that those
imports backed remained INFERRED, so downstream consumers couldn't tell
high-evidence calls apart from name-match guesses.

This pass runs after the file-id remap (line 4736), so we relativize
node `source_file` paths before computing file_nids — otherwise the
caller's computed file_nid (absolute-path-derived) wouldn't match the
imports_from edge source (already remapped to relative form).

Promotion rule:
  - Symbol-level `imports` edge from caller's file -> callee node id
    => EXTRACTED, confidence_score 1.0
  - Module-level `imports_from` edge from caller's file -> callee's file
    => EXTRACTED, confidence_score 1.0
  - Otherwise => INFERRED, confidence_score 0.8 (existing behavior)

Validated on a 92-file CJS orchestrator: 5 previously-INFERRED edges
from runExecute() now resolve to EXTRACTED, and 88% of cross-file calls
in the corpus (104 of 118) promote, leaving INFERRED only for genuine
heuristic guesses with no import backing.

Adds two tests:
  - test_cross_file_call_promoted_to_extracted_with_import_evidence
  - test_cross_file_call_remains_inferred_without_import_evidence

tests/test_extract.py

@@ -240,3 +240,52 @@ def test_extract_js_arrow_function_still_extracted():
         assert "greet()" in labels
     finally:
         arrow_fixture.unlink()
+
+
+def test_cross_file_call_promoted_to_extracted_with_import_evidence(tmp_path):
+    """A cross-file `calls` edge must be EXTRACTED when the caller's file has
+    an `imports` or `imports_from` edge linking it to the callee."""
+    caller = tmp_path / "caller.js"
+    callee = tmp_path / "lib.js"
+    caller.write_text(
+        "const { doWork } = require('./lib');\n"
+        "function run() { doWork(); }\n"
+    )
+    callee.write_text(
+        "function doWork() { return 1; }\n"
+        "module.exports = { doWork };\n"
+    )
+    result = extract([caller, callee], cache_root=tmp_path)
+    nodes = {n["id"]: n for n in result["nodes"]}
+    call_edges = [
+        e for e in result["edges"]
+        if e["relation"] == "calls"
+        and nodes[e["source"]]["label"] == "run()"
+        and nodes[e["target"]]["label"] == "doWork()"
+    ]
+    assert len(call_edges) == 1
+    assert call_edges[0]["confidence"] == "EXTRACTED"
+    assert call_edges[0]["confidence_score"] == 1.0
+
+
+def test_cross_file_call_remains_inferred_without_import_evidence(tmp_path):
+    """A cross-file `calls` edge must stay INFERRED when there is no import
+    edge — name collision alone is insufficient evidence."""
+    caller = tmp_path / "caller.js"
+    callee = tmp_path / "lib.js"
+    # Caller does NOT require lib — same-name function happens to exist elsewhere
+    caller.write_text("function run() { doUnique(); }\n")
+    callee.write_text(
+        "function doUnique() { return 1; }\n"
+        "module.exports = { doUnique };\n"
+    )
+    result = extract([caller, callee], cache_root=tmp_path)
+    nodes = {n["id"]: n for n in result["nodes"]}
+    call_edges = [
+        e for e in result["edges"]
+        if e["relation"] == "calls"
+        and nodes[e["source"]]["label"] == "run()"
+        and nodes[e["target"]]["label"] == "doUnique()"
+    ]
+    assert len(call_edges) == 1
+    assert call_edges[0]["confidence"] == "INFERRED"