feat: add pink-purple theme, fix image paste race condition, allow @/commands anywhere in input

- Add Pink Purple theme (hot pink/purple/magenta on dark plum background)
- Fix race condition where clearPastedImages() in input-area ran before
  the async message handler could read the images, silently dropping them
- Allow @ file picker and / command menu to trigger at any cursor position,
  not just when the input is empty
- Update CHANGELOG and README with new changes

src/types/tui.ts

@@ -212,6 +212,7 @@ export interface PlanApprovalPrompt {
   id: string;
   planTitle: string;
   planSummary: string;
+  planContent?: string;
   planFilePath?: string;
   resolve: (response: PlanApprovalPromptResponse) => void;
 }
@@ -255,6 +256,21 @@ export interface SessionStats {
   contextMaxTokens: number;
 }
 
+// ============================================================================
+// Modified File Tracking
+// ============================================================================
+
+export interface ModifiedFileEntry {
+  /** Relative or absolute file path */
+  filePath: string;
+  /** Net lines added */
+  additions: number;
+  /** Net lines deleted */
+  deletions: number;
+  /** Timestamp of the last modification */
+  lastModified: number;
+}
+
 // ============================================================================
 // Streaming Types
 // ============================================================================