feat(scenario): step output, getStepOutput helper, export/import MCP tools, doc restructure

- add output column to ScenarioRunStepEntity; exec step return value is JSON-serialised and stored
- expose helpers.getStepOutput(order) in exec code; negative order is relative to current step
- add get_scenario_run, wait_for_scenario_run, export_scenario, import_scenario MCP tools
- move Architecture, Key descriptors, MCP tools, Scenario, Development docs to docs/
- delete CONTRIBUTING.md (replaced by docs/development.md)

test/dom-helpers.spec.ts

@@ -139,16 +139,18 @@ function makePage(rootEl: FakeEl) {
 
   const evaluate = jest
     .fn()
-    .mockImplementation((fn: (...args: unknown[]) => unknown, args: unknown) => {
-      const exec = new Function(
-        "document",
-        "window",
-        "Node",
-        "__args__",
-        `return (${fn.toString()})(__args__)`,
-      );
-      return Promise.resolve(exec(fakeDocument, fakeWindow, fakeNode, args));
-    });
+    .mockImplementation(
+      (fn: (...args: unknown[]) => unknown, args: unknown) => {
+        const exec = new Function(
+          "document",
+          "window",
+          "Node",
+          "__args__",
+          `return (${fn.toString()})(__args__)`,
+        );
+        return Promise.resolve(exec(fakeDocument, fakeWindow, fakeNode, args));
+      },
+    );
 
   return { evaluate } as unknown as import("playwright").Page;
 }