[Proposal] Add warning message when setParam fails silently

还没有人认领这个 Issue。

**Description**
While working on PEP8 cleanups in `netpyne/specs/netParams.py`, I noticed that `setParam` and similar methods fail silently when a label is not found.

**Current Behavior**
```python
if label in self:
d = self[label]
else:
return False # Silently fails, user is not notified
```

**Proposed Improvement**
I propose adding an explicit warning so users can debug their scripts easier:

```python
else:
print(f\"Warning: Label '{label}' not found. Parameter '{param}' not set.\")
return False
```

**Question**
Should I include this UX improvement as part of the PEP8 cleanup PR, or would you prefer a separate PR for this logic change?"

从 netpyne/specs/netParams.py 开始，阅读 setParam 以及 issue 中描述的类似方法。确认缺少 label 时的预期行为，然后验证是否会发出警告，并且该方法仍会返回 False 而不会设置参数。

由索引模型根据 Issue 内容生成。