Add TUI rendering for CustomMessageEntry

- Add CustomMessageComponent with purple-tinted styling
- Add theme colors: customMessageBg, customMessageText, customMessageLabel
- Rename renderMessages to renderSessionContext taking SessionContext directly
- renderInitialMessages now gets context from sessionManager
- Skip rendering for display: false entries

packages/coding-agent/src/modes/interactive/theme/theme-schema.json

@@ -47,6 +47,9 @@
 				"text",
 				"userMessageBg",
 				"userMessageText",
+				"customMessageBg",
+				"customMessageText",
+				"customMessageLabel",
 				"toolPendingBg",
 				"toolSuccessBg",
 				"toolErrorBg",
@@ -122,6 +125,18 @@
 					"$ref": "#/$defs/colorValue",
 					"description": "User message text color"
 				},
+				"customMessageBg": {
+					"$ref": "#/$defs/colorValue",
+					"description": "Custom message background (hook-injected messages)"
+				},
+				"customMessageText": {
+					"$ref": "#/$defs/colorValue",
+					"description": "Custom message text color"
+				},
+				"customMessageLabel": {
+					"$ref": "#/$defs/colorValue",
+					"description": "Custom message type label color"
+				},
 				"toolPendingBg": {
 					"$ref": "#/$defs/colorValue",
 					"description": "Tool execution box (pending state)"