chore: drop non-code junk (pi-mono-reference, runtime state, root duplicates)

Remove files that should never have been tracked:

- pi-mono-reference/: 688-file copy of an upstream monorepo, zero imports,
  used only as offline human reference
- build/electron-builder.runtime.json: environment-specific build artifact
  with hardcoded local paths
- state/cancel-signal-state.json: runtime state written by the app
- prompt.txt, logo.svg (root): exact duplicates of the canonical copies
  under .planning/archive/ and assets/

Add state/ to .gitignore so future runtime state stays out.

pi-mono-reference/packages/coding-agent/test/interactive-mode-anthropic-warning.test.ts

@@ -1,73 +0,0 @@
-import { describe, expect, test, vi } from "vitest";
-import { InteractiveMode } from "../src/modes/interactive/interactive-mode.js";
-
-describe("InteractiveMode.maybeWarnAboutAnthropicSubscriptionAuth", () => {
-	test("warns once when Anthropic subscription auth is detected", async () => {
-		const fakeThis: any = {
-			anthropicSubscriptionWarningShown: false,
-			session: {
-				modelRegistry: {
-					authStorage: {
-						get: vi.fn().mockReturnValue(undefined),
-					},
-					getApiKeyForProvider: vi.fn().mockResolvedValue("sk-ant-oat01-test"),
-				},
-			},
-			showWarning: vi.fn(),
-		};
-
-		await (InteractiveMode as any).prototype.maybeWarnAboutAnthropicSubscriptionAuth.call(fakeThis, {
-			provider: "anthropic",
-		});
-		await (InteractiveMode as any).prototype.maybeWarnAboutAnthropicSubscriptionAuth.call(fakeThis, {
-			provider: "anthropic",
-		});
-
-		expect(fakeThis.showWarning).toHaveBeenCalledTimes(1);
-		expect(fakeThis.session.modelRegistry.getApiKeyForProvider).toHaveBeenCalledTimes(1);
-	});
-
-	test("warns when Anthropic OAuth is stored even if token refresh lookup would fail", async () => {
-		const fakeThis: any = {
-			anthropicSubscriptionWarningShown: false,
-			session: {
-				modelRegistry: {
-					authStorage: {
-						get: vi.fn().mockReturnValue({ type: "oauth" }),
-					},
-					getApiKeyForProvider: vi.fn().mockResolvedValue(undefined),
-				},
-			},
-			showWarning: vi.fn(),
-		};
-
-		await (InteractiveMode as any).prototype.maybeWarnAboutAnthropicSubscriptionAuth.call(fakeThis, {
-			provider: "anthropic",
-		});
-
-		expect(fakeThis.showWarning).toHaveBeenCalledTimes(1);
-		expect(fakeThis.session.modelRegistry.getApiKeyForProvider).not.toHaveBeenCalled();
-	});
-
-	test("does not warn for non-Anthropic models", async () => {
-		const fakeThis: any = {
-			anthropicSubscriptionWarningShown: false,
-			session: {
-				modelRegistry: {
-					authStorage: {
-						get: vi.fn(),
-					},
-					getApiKeyForProvider: vi.fn(),
-				},
-			},
-			showWarning: vi.fn(),
-		};
-
-		await (InteractiveMode as any).prototype.maybeWarnAboutAnthropicSubscriptionAuth.call(fakeThis, {
-			provider: "openai",
-		});
-
-		expect(fakeThis.showWarning).not.toHaveBeenCalled();
-		expect(fakeThis.session.modelRegistry.getApiKeyForProvider).not.toHaveBeenCalled();
-	});
-});