perf: reduce resident dependencies and duplicate WebSocket authentication (#3071)

* perf: load HTTP dependencies only in the HTTP worker

* docs: record 30-minute idle resource comparison

* perf: isolate database initialization from the cluster primary

* docs: record isolated database startup resource comparison

* perf: avoid an extra shell child in Docker health probes

* perf: load notification dependencies only when needed

* perf: retain queue cleanup after notification loading comparison

* fix: stop page polling after unmount and avoid duplicate fetches

* perf: share WebSocket session polling across connections

* docs: measure real WebSocket container CPU and memory

* perf: reuse JWT validation within each WebSocket session check

* perf: bound login IP lookup allocations with an address cache

* refactor: limit resource optimization PR to three core changes

* docs: benchmark the three core optimizations against develop

* chore: remove documentation and benchmark artifacts from PR

back/shared/startupProcess.ts

@@ -0,0 +1,47 @@
+import { fork } from 'child_process';
+
+// Keep one-off startup dependencies out of the long-lived cluster primary.
+export function runStartupProcess(entrypoint: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const child = fork(entrypoint, [], { stdio: 'inherit' });
+    let interrupted: NodeJS.Signals | undefined;
+    let killTimer: NodeJS.Timeout | undefined;
+
+    const terminate = (signal: NodeJS.Signals) => {
+      if (interrupted) return;
+      interrupted = signal;
+      child.kill(signal);
+      killTimer = setTimeout(() => child.kill('SIGKILL'), 8000);
+      killTimer.unref();
+    };
+    const onSigterm = () => terminate('SIGTERM');
+    const onSigint = () => terminate('SIGINT');
+    const onExit = () => child.kill('SIGKILL');
+    const cleanup = () => {
+      if (killTimer) clearTimeout(killTimer);
+      process.removeListener('SIGTERM', onSigterm);
+      process.removeListener('SIGINT', onSigint);
+      process.removeListener('exit', onExit);
+    };
+
+    process.once('SIGTERM', onSigterm);
+    process.once('SIGINT', onSigint);
+    process.once('exit', onExit);
+    child.once('error', (error) => {
+      cleanup();
+      reject(error);
+    });
+    child.once('close', (code, signal) => {
+      cleanup();
+      if (code === 0 && !interrupted) {
+        resolve();
+      } else {
+        reject(
+          new Error(
+            `Startup process failed (${interrupted || signal || code})`,
+          ),
+        );
+      }
+    });
+  });
+}