fix: keep engine boot clean, test owns try

Remove the try-catch wrapper added around s.waitForBoot in
sound_algo/engine.scd — it swallowed real boot errors in
production. Move boot-failure tolerance into
sound_algo/tests/test_tempo.scd instead, where it belongs.
data_only/engine.scd was not affected (no wrapper added).

sound_algo/engine.scd

@@ -20,8 +20,7 @@
     ~bpm;
 };
 
-// Protection defensive : evite la propagation si le boot reseau echoue
-try { s.waitForBoot {
+s.waitForBoot {
 
     // ----- Acid 303 -----
     // Env ADSR sur l'amp avec doneAction:2 -- garanti pas de fuite
@@ -304,6 +303,6 @@ try { s.waitForBoot {
     //   (charges automatiquement par 00_load.scd > CHARGER TOUT)
 
     "=== setup OK -- lance le bloc PLAY ===".postln;
-} } { |e| ("[engine] avertissement boot serveur : " ++ e.errorString).postln };
+};
 )
 

sound_algo/tests/test_tempo.scd

@@ -2,7 +2,8 @@
 (
 var ok = true;
 // minimal: ~setTempo only needs TempoClock.default (always exists)
-(thisProcess.nowExecutingPath.dirname.dirname ++ "/engine.scd").load;
+try { (thisProcess.nowExecutingPath.dirname.dirname ++ "/engine.scd").load } { |e|
+    ("[test] engine boot skipped: " ++ e.errorString).postln };
 ~setTempo.(140);
 if(~bpm != 140) { ok = false; "FAIL: bpm".postln };
 if(TempoClock.default.tempo.round(0.0001) != (140/60).round(0.0001)) {