fix: Ralph wizard uses file-based prompt to avoid screen escaping issues

- Add /api/sessions/:id/ralph-prompt/write endpoint to write prompt to @ralph_prompt.md
- Wizard now writes full prompt to file, then sends simple read command to Claude
- Fix session readiness check to wait for prompt character instead of notWorking flag
- Add E2E test infrastructure for ralph-loop workflow (port 3190)
- Add ralph-wizard-prod.mjs script for production testing

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

test/e2e/fixtures/pixelmatch.d.ts

@@ -0,0 +1,25 @@
+/**
+ * Type declarations for pixelmatch
+ */
+declare module 'pixelmatch' {
+  interface PixelmatchOptions {
+    threshold?: number;
+    includeAA?: boolean;
+    alpha?: number;
+    aaColor?: [number, number, number];
+    diffColor?: [number, number, number];
+    diffColorAlt?: [number, number, number] | null;
+    diffMask?: boolean;
+  }
+
+  function pixelmatch(
+    img1: Uint8Array | Uint8ClampedArray | Buffer,
+    img2: Uint8Array | Uint8ClampedArray | Buffer,
+    output: Uint8Array | Uint8ClampedArray | Buffer | null,
+    width: number,
+    height: number,
+    options?: PixelmatchOptions
+  ): number;
+
+  export = pixelmatch;
+}