feat: embed daemon JS in binary, eliminate npm install of camoufox-browser

The daemon JS files (daemon.js, server.js, browser.js, protocol.js,
snapshot.js, ipc.js) are now EMBEDDED in the compiled Rust binary via
include_dir! and extracted to ~/.gyandoot/daemon/ on first run.

This eliminates the need to npm install -g camoufox-browser@0.1.0,
which bundles an incompatible camoufox-js@0.9.3 that caused:
- 'Cannot open database' errors
- Re-downloading 298MB browser on every navigation
- Circular install/remove/install loops

Now the daemon imports camoufox-js from the global npm install (v0.11.0)
which is installed by install.sh. Clean, no bundled deps, no conflicts.

Also removed: is_npm_package_installed(), install_npm_package(),
find_daemon_js() — all replaced by gyandoot_browser::daemon::extract_daemon()

crates/gyandoot-browser/daemon/protocol.js

@@ -0,0 +1,46 @@
+import { z } from "zod";
+const commandSchema = z
+    .object({
+    id: z.string(),
+    action: z.string()
+})
+    .passthrough();
+export function parseCommand(input) {
+    let json;
+    try {
+        json = JSON.parse(input);
+    }
+    catch {
+        return { success: false, error: "Invalid JSON" };
+    }
+    const id = typeof json === "object" && json !== null && "id" in json
+        ? String(json.id)
+        : undefined;
+    const result = commandSchema.safeParse(json);
+    if (!result.success) {
+        const errors = result.error.errors.map((e) => `${e.path.join(".")}: ${e.message}`).join(", ");
+        return { success: false, error: `Validation error: ${errors}`, id };
+    }
+    return { success: true, command: result.data };
+}
+export function successResponse(id, data) {
+    return { id, success: true, data };
+}
+export function errorResponse(id, error) {
+    return { id, success: false, error };
+}
+/**
+ * Serialize a response to JSON string.
+ * Replaces lone Unicode surrogates with U+FFFD to avoid serde_json parse errors.
+ */
+function sanitizeUtf16(input) {
+    // Fast path: most strings contain no surrogate code units.
+    if (!/[\uD800-\uDFFF]/.test(input))
+        return input;
+    // Replace lone high/low surrogates. Valid surrogate pairs are preserved.
+    // Ref: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toWellFormed
+    return input.replace(/[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?<![\uD800-\uDBFF])[\uDC00-\uDFFF]/g, "\uFFFD");
+}
+export function serializeResponse(response) {
+    return JSON.stringify(response, (_key, value) => typeof value === "string" ? sanitizeUtf16(value) : value);
+}