Post-1.0: Localhost seccomp on K8s, warm sandbox pool, server HPA

- K8sDriver.with_localhost_seccomp(profile): sandbox pods run under the
  STRICT allowlist instead of the runtime default. Proven live on kind:
  the harness installs the profile onto the node, a pod runs ordinary
  work as uid 10001, and unshare is kernel-denied inside the pod — the
  same probe the Docker suite uses, now passing on both targets
- Helm: sandbox.seccomp=localhost renders a DaemonSet that installs the
  chart-shipped profile into /var/lib/kubelet/seccomp on every node
  (ConfigMap + hostPath); ci/check-helm.sh enforces the chart copy stays
  byte-identical to images/seccomp/agent-profile.json and asserts the
  hardened render (DaemonSet + profile + HPA)
- server HPA (autoscaling/v2, CPU target) behind
  server.autoscaling.enabled
- SandboxManager.warm(n): a background warmer keeps n pre-provisioned
  sandboxes ready so an agent's first exec skips container startup;
  unhealthy pool entries are discarded, reuse never drains the pool,
  shutdown destroys assigned AND pooled. [sandbox] warm_pool config
  (default 0). Real-Docker test: prefill -> assign -> refill -> reuse ->
  clean shutdown

160 Rust tests + 4 live kind tests.

Co-Authored-By: Claude Fable 5 <[email protected]>

crates/bins/teamclaw-server/src/main.rs

@@ -90,11 +90,17 @@ async fn run() -> Result<(), String> {
             Ok(driver) => {
                 let driver: std::sync::Arc<dyn tc_sandbox::SandboxDriver> =
                     std::sync::Arc::new(driver);
+                let agents = std::sync::Arc::new(tc_runtime::SandboxManager::new(
+                    driver.clone(),
+                    &config.sandbox.image,
+                ));
+                let agents = if config.sandbox.warm_pool > 0 {
+                    agents.warm(config.sandbox.warm_pool)
+                } else {
+                    agents
+                };
                 (
-                    Some(std::sync::Arc::new(tc_runtime::SandboxManager::new(
-                        driver.clone(),
-                        &config.sandbox.image,
-                    ))),
+                    Some(agents),
                     Some(std::sync::Arc::new(
                         tc_runtime::SandboxManager::new(driver, &config.sandbox.browser_image)
                             .with_egress(),