chore: bump version to 0.43.0 (bd-lejq)

- Update Version in cmd/bd/version.go: 0.42.0 → 0.43.0
- Update CHANGELOG.md with 0.43.0 section
- Fix test isolation in TestTrackBdVersion_NoBeadsDir

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/version.go

@@ -14,7 +14,7 @@ import (
 
 var (
 	// Version is the current version of bd (overridden by ldflags at build time)
-    Version = "0.42.0"
+    Version = "0.43.0"
 	// Build can be set via ldflags at compile time
 	Build = "dev"
 	// Commit and branch the git revision the binary was built from (optional ldflag)