fix(tests): resolve short test performance regression (bd-0v4)

Short tests were timing out after 13+ minutes due to:

1. TestZFCSkipsExportAfterImport spawning subprocess that tried to
   auto-start daemon - now skipped in short mode

2. TestVersionFlag taking 5+ seconds because --version flag did not
   skip PersistentPreRun daemon startup - added early return

3. TestGetVersionsSince* had hardcoded version expectations that
   became stale - made tests dynamic using versionChanges array

Short tests now complete in ~8 seconds instead of timing out.

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

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

cmd/bd/main.go

@@ -221,6 +221,11 @@ var rootCmd = &cobra.Command{
 			return
 		}
 
+		// Also skip for --version flag on root command (cmdName would be "bd")
+		if v, _ := cmd.Flags().GetBool("version"); v {
+			return
+		}
+
 		// Auto-detect sandboxed environment (bd-u3t: Phase 2 for GH #353)
 		// Only auto-enable if user hasn't explicitly set --sandbox or --no-daemon
 		if !cmd.Flags().Changed("sandbox") && !cmd.Flags().Changed("no-daemon") {