chore: replace upstream pre-push hook with Neuron guard, drop husky and vendor .github metadata

.githooks/pre-push

@@ -0,0 +1,15 @@
+#!/bin/sh
+# Neuron Technologies pre-push guard.
+# Warns on bun version drift and blocks pushes that break the build.
+
+set -e
+
+BUN_EXPECTED=$(bun -e 'const pkg = await Bun.file("package.json").json(); console.log(pkg.packageManager?.split("@")[1] ?? "")')
+if [ -n "$BUN_EXPECTED" ]; then
+  if ! bun -e "import { semver } from 'bun'; if (!semver.satisfies(process.versions.bun, '^$BUN_EXPECTED')) process.exit(1)" 2>/dev/null; then
+    echo "WARNING: bun $(bun --version) does not satisfy ^$BUN_EXPECTED — continuing, but consider aligning your toolchain."
+  fi
+fi
+
+echo "Running typecheck before push..."
+bun typecheck