Fix critical double-release race in importInProgress flag

CRITICAL BUG: The previous fix had a race condition where the
importInProgress flag could be released twice, allowing two goroutines
to think they both hold the lock.

Bug scenario:
1. Goroutine A: acquires lock (CAS true)
2. Goroutine A: manually releases at line 208 for git dirty skip
3. Goroutine B: CAS succeeds, acquires lock
4. Goroutine A: defer runs, releases flag AGAIN (clears B lock)
5. Goroutine C: CAS succeeds - now TWO goroutines have lock

Root cause: Using both manual Store(false) AND defer Store(false)
created a window where the flag could be cleared twice.

Fix: Use a shouldDeferRelease flag to disable the deferred release
when we manually release early. This ensures exactly one release
per acquisition.

Testing: All auto-import tests still passing

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.beads/daemon-stderr.log

@@ -0,0 +1,2 @@
+Error: daemon already running (PID 27867)
+Use 'bd daemon --stop' to stop it first