test(core): trim redundant test resets and use mockClear

src/process/kill-tree.test.ts

@@ -25,7 +25,7 @@ describe("killProcessTree", () => {
   let killSpy: ReturnType<typeof vi.spyOn>;
 
   beforeEach(() => {
-    spawnMock.mockReset();
+    spawnMock.mockClear();
     killSpy = vi.spyOn(process, "kill");
     vi.useFakeTimers();
   });

src/process/supervisor/supervisor.pty-command.test.ts

@@ -40,7 +40,7 @@ describe("process supervisor PTY command contract", () => {
   });
 
   beforeEach(() => {
-    createPtyAdapterMock.mockReset();
+    createPtyAdapterMock.mockClear();
   });
 
   it("passes PTY command verbatim to shell args", async () => {