test(hands): add 28 unit tests for Twitter Hand

Cover config defaults, 13 action types deserialization, serialization
roundtrip, credential management, and data type parsing. Also add
PartialEq derive to HandStatus for test assertions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/zclaw-hands/src/hand.rs

@@ -111,7 +111,7 @@ impl HandResult {
 }
 
 /// Hand execution status
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
 pub enum HandStatus {
     Idle,