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.

core/chanora_core/src/lib.rs

@@ -68,8 +68,8 @@ pub use chanora_diagnostics::{
     RedactingLogLayer, Redactor, DEFAULT_LOG_CAPACITY,
 };
 pub use chanora_protocol::{
-    ChannelInfo, ChatMessage, ClientInfo, ClientProfile, ConnectConfig, DisconnectReason,
-    MessageTarget, PokeStrength, ProtocolError, ServerActivity, ServerSnapshot,
+    validate_nickname, ChannelInfo, ChatMessage, ClientInfo, ClientProfile, ConnectConfig,
+    DisconnectReason, MessageTarget, PokeStrength, ProtocolError, ServerActivity, ServerSnapshot,
 };
 pub use chanora_storage::{Bookmark, BookmarkRepository, IdentityFileStore};
 pub use events::{