Add chapter checkpoint feature

- New feature: bookmark messages to exclude earlier history from context
- Saves tokens by marking chapter start points in long chats
- Uses SillyTavern's /hide and /unhide slash commands
- Persists checkpoint across page reloads and generation events
- UI: bookmark icon in message menus with visual indicators
- Debounced restore function prevents concurrent executions
- Pre-generation checkpoint application ensures messages stay hidden
- Clean production-ready code with proper error handling

src/core/config.js

@@ -42,6 +42,7 @@ export const defaultSettings = {
     // This setting helps compatibility with other extensions like GuidedGenerations.
     skipInjectionsForGuided: 'none',
     enablePlotButtons: true, // Show plot progression buttons above chat input
+    saveTrackerHistory: false, // Save tracker data in chat history for each message
     panelPosition: 'right', // 'left', 'right', or 'top'
     theme: 'default', // Theme: default, sci-fi, fantasy, cyberpunk, custom
     customColors: {

src/core/state.js

@@ -24,6 +24,7 @@ export let extensionSettings = {
     customHtmlPrompt: '', // Custom HTML prompt text (empty = use default)
     skipInjectionsForGuided: 'none', // skip injections for instruct injections and quiet prompts (GuidedGenerations compatibility)
     enablePlotButtons: true, // Show plot progression buttons above chat input
+    saveTrackerHistory: false, // Save tracker data in chat history for each message
     panelPosition: 'right', // 'left', 'right', or 'top'
     theme: 'default', // Theme: default, sci-fi, fantasy, cyberpunk, custom
     customColors: {