Add legacy_tool.dot workflow and CLI tests for backwards compat

Exercises the old tool_command attribute through validate and
dry-run to catch regressions in the tool → script compatibility.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/attractor/tests/cli.rs

@@ -53,6 +53,15 @@ fn validate_styled() {
         .stderr(predicate::str::contains("Validation: OK"));
 }
 
+#[test]
+fn validate_legacy_tool() {
+    attractor()
+        .args(["validate", "../../test/legacy_tool.dot"])
+        .assert()
+        .success()
+        .stderr(predicate::str::contains("Validation: OK"));
+}
+
 #[test]
 fn validate_invalid() {
     attractor()
@@ -118,6 +127,14 @@ fn dry_run_styled() {
         .success();
 }
 
+#[test]
+fn dry_run_legacy_tool() {
+    attractor()
+        .args(["run", "--dry-run", "--auto-approve", "../../test/legacy_tool.dot"])
+        .assert()
+        .success();
+}
+
 // -- NDJSON logging ----------------------------------------------------------
 
 #[test]

test/legacy_tool.dot

@@ -0,0 +1,11 @@
+digraph LegacyTool {
+    graph [goal="Verify backwards compatibility with old tool naming"]
+    rankdir=LR
+
+    start [shape=Mdiamond, label="Start"]
+    exit  [shape=Msquare, label="Exit"]
+
+    echo_task [label="Echo", shape=parallelogram, tool_command="echo hello"]
+
+    start -> echo_task -> exit
+}