Add Brave CDP automation, replace Oracle browser mode

Connects to user's running Brave via Chrome DevTools Protocol
to automate ChatGPT interaction. Uses puppeteer-core to open a
tab, send the prompt, wait for response, and extract the result.

No cookies, no separate profiles, no copy/paste. Just connects
to the browser where the user is already logged in.

One-time setup: relaunch Brave with --remote-debugging-port=9222

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

node_modules/text-decoder/lib/pass-through-decoder.js

@@ -0,0 +1,19 @@
+const b4a = require('b4a')
+
+module.exports = class PassThroughDecoder {
+  constructor (encoding) {
+    this.encoding = encoding
+  }
+
+  get remaining () {
+    return 0
+  }
+
+  decode (tail) {
+    return b4a.toString(tail, this.encoding)
+  }
+
+  flush () {
+    return ''
+  }
+}