fix: remove leaky mock.module() for project-name that polluted parallel workers (#1299)

Top-level mock.module() in context-reinjection-guard.test.ts permanently stubbed
getProjectName() to 'test-project' for the entire Bun worker process, causing
tests in other files to receive the wrong value. Removed the unnecessary mock
(session-init tests don't assert on project name), added bunfig.toml smol=true
for worker isolation, and added a regression test.

Generated by Claude Code
Vibe coded by ousamabenyounes

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

tests/utils/project-name-isolation.test.ts

@@ -0,0 +1,28 @@
+/**
+ * Regression test for mock.module() worker pollution (#1299)
+ *
+ * context-reinjection-guard.test.ts used to call mock.module('../../src/utils/project-name.js', ...)
+ * at the top level, which permanently stubbed getProjectName to return 'test-project'
+ * for every subsequent import in the same Bun worker process.
+ *
+ * Without bunfig.toml [test] smol=true, this test would fail when Bun scheduled
+ * it in the same worker as context-reinjection-guard.test.ts, because the module
+ * was mocked before these tests ran and getProjectName() returned 'test-project'
+ * instead of the real extracted basename.
+ */
+import { describe, it, expect } from 'bun:test';
+import { getProjectName } from '../../src/utils/project-name.js';
+
+describe('getProjectName mock isolation (#1299)', () => {
+  it('returns real basename, not the leaked test-project mock', () => {
+    expect(getProjectName('/real/path/to/my-project')).toBe('my-project');
+  });
+
+  it('returns unknown-project for empty string (real implementation)', () => {
+    expect(getProjectName('')).toBe('unknown-project');
+  });
+
+  it('returns real basename from nested path', () => {
+    expect(getProjectName('/home/user/code/awesome-app')).toBe('awesome-app');
+  });
+});