Improve agent autonomy and diff view readability

Agent behavior improvements:
  - Add project context detection (tsconfig.json, pom.xml, etc.)
  - Enforce validation after changes (tsc --noEmit, mvn compile, etc.)
  - Run tests automatically - never ask "do you want me to run tests"
  - Complete full loop: create → type-check → test → confirm
  - Add command detection for direct execution (run tree, run ls)

  Diff view improvements:
  - Use darker backgrounds for added/removed lines
  - Add diffLineBgAdded, diffLineBgRemoved, diffLineText theme colors
  - Improve text visibility with white text on dark backgrounds
  - Update both React/Ink and SolidJS diff components

  Streaming fixes:
  - Fix tool call argument accumulation using OpenAI index field
  - Fix streaming content display after tool calls
  - Add consecutive error tracking to prevent token waste

  Other changes:
  - ESC to abort operations, Ctrl+C to exit
  - Fix model selection when provider changes in cascade mode
  - Add debug logging for troubleshooting
  - Move tests to root tests/ folder
  - Fix banner test GRADIENT_COLORS reference

src/interfaces/CopilotModels.ts

@@ -0,0 +1,32 @@
+/**
+ * Copilot Models API Interfaces
+ */
+
+export interface ModelBilling {
+  is_premium: boolean;
+  multiplier: number;
+  restricted_to?: string[];
+}
+
+export interface ModelCapabilities {
+  type?: string;
+  limits?: {
+    max_output_tokens?: number;
+  };
+  supports?: {
+    tool_calls?: boolean;
+    streaming?: boolean;
+  };
+}
+
+export interface ModelsApiModel {
+  id: string;
+  name?: string;
+  model_picker_enabled?: boolean;
+  billing?: ModelBilling;
+  capabilities?: ModelCapabilities;
+}
+
+export interface ModelsApiResponse {
+  data: ModelsApiModel[];
+}

src/interfaces/StreamCallbacksWithState.ts

@@ -0,0 +1,10 @@
+/**
+ * Stream callbacks with state tracking
+ */
+
+import type { StreamCallbacks } from "@/types/streaming";
+
+export interface StreamCallbacksWithState {
+  callbacks: StreamCallbacks;
+  hasReceivedContent: () => boolean;
+}

src/interfaces/StreamingChatOptions.ts

@@ -0,0 +1,10 @@
+/**
+ * Streaming Chat Options
+ */
+
+import type { AgentOptions } from "@interfaces/AgentOptions";
+import type { ModelSwitchInfo } from "@/types/streaming";
+
+export interface StreamingChatOptions extends AgentOptions {
+  onModelSwitch?: (info: ModelSwitchInfo) => void;
+}