feat(backend): scaffold PodMan agent pipeline + token server

Express server with /health and a LiveKit token endpoint. Module skeletons
for the full loop: vision (Gemini), GitHub fusion, collision detector (pure,
testable), intervention engine, and continual-learning memory store. Approve
native build scripts (esbuild/genai/protobufjs) at the workspace root.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/github/client.ts

@@ -0,0 +1,25 @@
+import { Octokit } from 'octokit';
+import type { GithubStateSnapshot } from '@podman/shared';
+import { env } from '../env.js';
+
+export const octokit: Octokit = new Octokit({ auth: env.github.token });
+
+/**
+ * Pull the GitHub state relevant to a file in the pod's repo: open branches
+ * and PRs touching it. Fused with vision contexts by the collision detector.
+ *
+ * TODO(github): list branches/PRs, diff files, map commits -> engineer logins.
+ */
+export async function getStateForFile(_file: string): Promise<GithubStateSnapshot> {
+  return { branches: {}, openPrs: [], unpushed: false };
+}
+
+/** Open a draft "sync PR" between two engineers' branches — the suggested action. */
+export async function openSyncPr(_params: {
+  base: string;
+  head: string;
+  title: string;
+}): Promise<{ number: number; url: string } | null> {
+  // TODO(github): octokit.rest.pulls.create({ ...env.github.repo, draft: true })
+  return null;
+}