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>

bunfig.toml

@@ -0,0 +1,7 @@
+[test]
+# Force each test file into its own worker process.
+# Prevents mock.module() calls (which are permanent within a worker)
+# from leaking across test files in parallel runs.
+# Note: smol=true increases test startup time by spawning one Bun process per file.
+# See: https://github.com/thedotmack/claude-mem/issues/1299
+smol = true