Add experimental durable exe.dev agent environments

Keep one VM per environment with independent lease cgroups, persistent workspaces, immutable runner images, and an explicit experimental gate. Add live compatibility, recovery, browser-preview, and stress campaigns.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

scripts/check-node-version-policy.mjs

@@ -64,7 +64,7 @@ const requiredSourceFragments = [
   ["scripts/install.sh", "DEFAULT_NODE_MAJOR=24"],
   ["docker/agent-runtime/Dockerfile.base", "ARG NODE_VERSION=24"],
   ["packages/adapter-utils/src/sandbox-install-command.ts", "NODE_VERSION=\"v24.11.0\""],
-  ["packages/plugins/sandbox-providers/exe-dev/src/plugin.ts", "nodesource.com/setup_24.x"],
+  ["docker/exe-dev-runner/Dockerfile", "FROM node:24-bookworm@sha256:"],
   ["packages/plugins/sandbox-providers/modal/src/manifest.ts", 'default: "node:24"'],
   ["cli/esbuild.config.mjs", 'target: "node24"'],
   ["packages/plugins/sdk/src/bundlers.ts", 'target: "node24"'],