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/interfaces/AgentResult.ts

@@ -4,9 +4,21 @@
 
 import type { ToolCall, ToolResult } from "@/types/tools";
 
+/** Why the agent loop stopped */
+export type AgentStopReason =
+  | "completed"           // LLM returned a final response (no more tool calls)
+  | "max_iterations"      // Hit the iteration limit
+  | "consecutive_errors"  // Repeated tool failures
+  | "aborted"             // User abort
+  | "error"               // Unrecoverable error
+  | "plan_approval"       // Stopped to request plan approval
+  ;
+
 export interface AgentResult {
   success: boolean;
   finalResponse: string;
   iterations: number;
   toolCalls: { call: ToolCall; result: ToolResult }[];
+  /** Why the agent stopped — helps the user understand what happened */
+  stopReason?: AgentStopReason;
 }

src/interfaces/StreamCallbacksWithState.ts

@@ -7,4 +7,5 @@ import type { StreamCallbacks } from "@/types/streaming";
 export interface StreamCallbacksWithState {
   callbacks: StreamCallbacks;
   hasReceivedContent: () => boolean;
+  hasReceivedUsage: () => boolean;
 }

src/interfaces/api/copilot/core.ts

@@ -0,0 +1,36 @@
+import type {
+  Message,
+  MessageContent,
+  ChatCompletionOptions,
+  ChatCompletionResponse,
+} from "@/types/providers";
+
+export interface FormattedMessage {
+  role: string;
+  content: MessageContent;
+  tool_call_id?: string;
+  tool_calls?: Message["tool_calls"];
+}
+
+export interface ChatRequestBody {
+  model: string;
+  messages: FormattedMessage[];
+  max_tokens: number;
+  temperature: number;
+  stream: boolean;
+  tools?: ChatCompletionOptions["tools"];
+  tool_choice?: string;
+}
+
+export interface ChatApiResponse {
+  error?: { message?: string };
+  choices?: Array<{
+    message?: { content?: string; tool_calls?: Message["tool_calls"] };
+    finish_reason?: ChatCompletionResponse["finishReason"];
+  }>;
+  usage?: {
+    prompt_tokens?: number;
+    completion_tokens?: number;
+    total_tokens?: number;
+  };
+}