fix: add visual indicators for custom mode sources (#6502)

- Add (G)/(P) indicators in mode dropdown for custom modes
- Add (Global)/(Project) text in selected mode button
- Built-in modes show no indicators
- Add helper functions getModeSource() and getSourceDisplayText()
- Use text-vscode-descriptionForeground for subtle styling
- Add comprehensive tests for source indicator functionality
- Add translation keys to all 18 supported languages

Author: MuriloFP

src/i18n/locales/ca/common.json

@@ -154,7 +154,9 @@
 		},
 		"scope": {
 			"project": "project",
-			"global": "global"
+			"global": "global",
+			"projectShort": "P",
+			"globalShort": "G"
 		}
 	},
 	"marketplace": {