Add thinkingText theme token, fix streaming toggle bug

- Add configurable thinkingText color for thinking blocks (defaults to muted)
- Make 'Thinking...' label italic when collapsed
- Fix Ctrl+T during streaming hiding the current message
- Track streamingMessage to properly re-render on toggle

Based on #366 by @paulbettner

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

@@ -29,6 +29,7 @@
 		"muted": "gray",
 		"dim": "dimGray",
 		"text": "",
+		"thinkingText": "gray",
 
 		"selectedBg": "selectedBg",
 		"userMessageBg": "userMsgBg",

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

@@ -28,6 +28,7 @@
 		"muted": "mediumGray",
 		"dim": "dimGray",
 		"text": "",
+		"thinkingText": "mediumGray",
 
 		"selectedBg": "selectedBg",
 		"userMessageBg": "userMsgBg",

packages/coding-agent/src/modes/interactive/theme/theme.ts

@@ -34,6 +34,7 @@ const ThemeJsonSchema = Type.Object({
 		muted: ColorValueSchema,
 		dim: ColorValueSchema,
 		text: ColorValueSchema,
+		thinkingText: ColorValueSchema,
 		// Backgrounds & Content Text (11 colors)
 		selectedBg: ColorValueSchema,
 		userMessageBg: ColorValueSchema,
@@ -98,6 +99,7 @@ export type ThemeColor =
 	| "muted"
 	| "dim"
 	| "text"
+	| "thinkingText"
 	| "userMessageText"
 	| "customMessageText"
 	| "customMessageLabel"