fix(protocol,bridge): wire nickname validation to connect (TODO-045)

Add validate_nickname() to ProtocolClient::connect() and bridge
connect(). Trim whitespace, reject empty, truncate to 30 chars.
Re-export validate_nickname from protocol and core.

crates/chanora_protocol/src/lib.rs

@@ -40,8 +40,8 @@ pub mod poke_limiter;
 
 pub use adapter::{ConnectConfig, DisconnectReason, InboundVoice, ProtocolClient, SnapshotProbe};
 pub use dto::{
-    ChannelId, ChannelInfo, ChatMessage, ClientId, ClientInfo, ClientProfile, MessageTarget,
-    PokeStrength, ProtocolDelta, ServerActivity, ServerSnapshot,
+    validate_nickname, ChannelId, ChannelInfo, ChatMessage, ClientId, ClientInfo, ClientProfile,
+    MessageTarget, PokeStrength, ProtocolDelta, ServerActivity, ServerSnapshot,
 };
 pub use poke_limiter::PokeLimiter;