M5: Patch Deployment & Job Management

Backend:
- migrations/003_jobs_scheduling.sql: retry_next_at/last_error columns,
  pg_notify trigger for immediate job dispatch, retry index
- pm-agent-client: ApplyPatchesRequest/Response, AgentJobStatus,
  RollbackResponse types; apply_patches/job_status/rollback_job
  client methods + generic POST helper
- pm-core/models: JobStatus, JobKind, PatchJob, PatchJobHost,
  CreateJobRequest, PatchJobSummary
- pm-web/routes/jobs.rs: POST/GET /api/v1/jobs, GET /jobs/:id,
  POST /jobs/:id/cancel, POST /jobs/:id/rollback
- pm-worker/job_executor.rs: NOTIFY listener, periodic scanner,
  execute_host_job, poll_running_jobs, handle_host_failure (3-retry
  exponential backoff 1m/5m/30m), sync_job_status, retry_pending_jobs
- pm-worker/main.rs: spawn job_executor

Frontend:
- types/index.ts: PatchInfo, PatchJobHost, PatchJob, PatchJobSummary,
  CreateJobRequest interfaces
- api/client.ts: jobsApi (list/get/create/cancel/rollback),
  patchesApi (getHostPatches)
- pages/PatchDeploymentPage.tsx: 3-step MUI Stepper
  (host select → configure → result)
- pages/JobsPage.tsx: job list table, expandable per-host detail,
  cancel/rollback actions with confirm dialog, load-more pagination
- App.tsx: /jobs and /deployment routes wired to real pages

cargo check: 0 errors | vite build: 0 errors

crates/pm-worker/src/main.rs

@@ -3,6 +3,12 @@
 //! Handles scheduled polling, job execution, maintenance window scheduling,
 //! retry logic, email notifications, and data pruning.
 
+mod agent_loader;
+mod health_poller;
+mod patch_poller;
+mod refresh_listener;
+mod job_executor;
+
 use pm_core::{
     config::AppConfig,
     db,
@@ -12,6 +18,11 @@ use sqlx::PgPool;
 use std::{sync::Arc, time::Duration};
 use tokio::time;
 
+use health_poller::run_health_poller;
+use patch_poller::run_patch_poller;
+use refresh_listener::run_refresh_listener;
+use job_executor::run_job_executor;
+
 /// Minimum number of applied migrations the worker requires before
 /// accepting work. Prevents the worker from running against a schema
 /// that hasn't been migrated yet.
@@ -51,14 +62,24 @@ async fn main() -> anyhow::Result<()> {
         config.worker.heartbeat_interval_secs,
     ));
 
-    // TODO M4: spawn health_poller, patch_data_poller
-    // TODO M5: spawn job_executor
-    // TODO M6: spawn job_scheduler
+    // M4: agent health poller, patch data poller, on-demand refresh listener
+    let health_handle = tokio::spawn(run_health_poller(pool.clone(), config.clone()));
+    let patch_handle = tokio::spawn(run_patch_poller(pool.clone(), config.clone()));
+    let refresh_handle = tokio::spawn(run_refresh_listener(pool.clone(), config.clone()));
+
+    // M5: job execution engine
+    let job_exec_handle = tokio::spawn(run_job_executor(pool.clone(), config.clone()));
 
     tracing::info!("Worker tasks started");
 
     // Wait for all tasks (they run indefinitely)
-    let _ = tokio::join!(heartbeat_handle);
+    let _ = tokio::join!(
+        heartbeat_handle,
+        health_handle,
+        patch_handle,
+        refresh_handle,
+        job_exec_handle,
+    );
 
     Ok(())
 }