test: prune low-value and duplicate tests

- Remove tautological test_trainer assertions that never trained
- Drop grpo isfinite-only smokes and merge frozen-model checks via parametrize
- Merge duplicate tool_parser cases (find/streaming/factory) with parametrize
- Collapse duplicate dataset store/detect_format tests
- Remove misleading scheduler/task tests that asserted the opposite of their names
- Merge signal-handler SIGTERM/SIGINT into one parametrized case
- Drop cross-file grpo strategy duplication kept in online_strategy

tests/module/test_lora.py

@@ -98,18 +98,9 @@ def test_loralinear_merge():
     assert lora._merged
     assert not hasattr(lora, "lora_A")
 
-
-def test_loralinear_merge_is_idempotent():
-    base = Linear(4, 4)
-    with torch.no_grad():
-        base.weight.zero_()
-
-    lora = LoRALinear(base, r=2, alpha=2)
-    with torch.no_grad():
-        lora.lora_B.fill_(1.0)
-
-    lora.merge()
+    # merge is guarded by _merged — a second call is a no-op.
     lora.merge()
+    assert lora._merged
 
 
 def test_inject_lora_default_target():