feat(cli): add branch push check before PR creation

src/pr.ts

@@ -25,6 +25,38 @@ export async function getBranchName(): Promise<string> {
   return result.trim();
 }
 
+export async function getBranchPushStatus(): Promise<{
+  pushed: boolean;
+  upstream: string | null;
+}> {
+  try {
+    const upstream = (await Bun.$`git rev-parse --abbrev-ref --symbolic-full-name @{u}`.quiet().text()).trim();
+    const localHead = (await Bun.$`git rev-parse HEAD`.quiet().text()).trim();
+    const remoteHead = (await Bun.$`git rev-parse @{u}`.quiet().text()).trim();
+    return { pushed: localHead === remoteHead, upstream };
+  } catch {
+    return { pushed: false, upstream: null };
+  }
+}
+
+export async function pushCurrentBranch(branch: string, upstream: string | null): Promise<void> {
+  const args = upstream
+    ? ["push"]
+    : ["push", "-u", "origin", branch];
+
+  const proc = Bun.spawn(["git", ...args], {
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  const exitCode = await proc.exited;
+  const stdout = await new Response(proc.stdout).text();
+  const stderr = await new Response(proc.stderr).text();
+
+  if (exitCode !== 0) {
+    throw new Error(stderr.trim() || stdout.trim() || `git push failed (exit code ${exitCode})`);
+  }
+}
+
 export async function getBranchCommits(base: string): Promise<string[]> {
   try {
     const result =