bruh you did the wrong thing

@copilot I intended for you to work on the following part of the thread:

• ActivationRegistry::activations_in_scope uses a.scope.contains(scope) without handling scope == NeuronScope::NONE. Because every bitflags value contains NONE (0 bits), calling activations_in_scope(NeuronScope::NONE) will currently return all activations, contradicting the documented meaning of NONE (“will not be randomly placed anywhere”).
  Fix: explicitly return an empty vec for scope == NeuronScope::NONE, or add a guard in the filter (e.g., scope != NONE && a.scope != NONE && a.scope.contains(scope)).
  src/activation.rs:206

• ActivationFn deserialization panics when an activation name is missing (panic!("Activation function {name} not found")). Panicking inside Deserialize makes malformed/untrusted input able to crash consumers; serde expects this to return a D::Error instead.
  Fix: replace the panic with Err(serde::de::Error::custom(...)) (and avoid unwrap() by using ok_or_else).

just add those changes to this PR.

@copilot I intended for you to work on the following part of the thread:

• ActivationRegistry::activations_in_scope uses a.scope.contains(scope) without handling scope == NeuronScope::NONE. Because...

Done in commit 4777194:

• activations_in_scope now returns an empty Vec when scope == NeuronScope::NONE, and also filters out activations whose own scope is NONE
• ActivationFn::deserialize now returns Err(serde::de::Error::custom(...)) instead of panicking when the activation name isn't found