major: kestrel is now a tak server (#6)

## Added

- CoT (Cursor on Target) server on port 8089 enabling ATAK/iTAK device connectivity
- Support for TAK stream protocol and traditional XML CoT messages
- TLS/SSL support with automatic fallback to plain TCP
- Username/password authentication for CoT connections
- Real-time device position tracking with TTL-based expiration (90s default)
- API endpoints: `/api/cot/config`, `/api/cot/server-package`, `/api/cot/truststore`, `/api/me/cot-password`
- TAK Server section in Settings with QR code for iTAK setup
- ATAK password management in Account page for OIDC users
- CoT device markers on map showing real-time positions
- Comprehensive documentation in `docs/` directory
- Environment variables: `COT_PORT`, `COT_TTL_MS`, `COT_REQUIRE_AUTH`, `COT_SSL_CERT`, `COT_SSL_KEY`, `COT_DEBUG`
- Dependencies: `fast-xml-parser`, `jszip`, `qrcode`

## Changed

- Authentication system supports CoT password management for OIDC users
- Database schema includes `cot_password_hash` field
- Test suite refactored to follow functional design principles

## Removed

- Consolidated utility modules: `authConfig.js`, `authSkipPaths.js`, `bootstrap.js`, `poiConstants.js`, `session.js`

## Security

- XML entity expansion protection in CoT parser
- Enhanced input validation and SQL injection prevention
- Authentication timeout to prevent hanging connections

## Breaking Changes

- Port 8089 must be exposed for CoT server. Update firewall rules and Docker/Kubernetes configurations.

## Migration Notes

- OIDC users must set ATAK password via Account settings before connecting
- Docker: expose port 8089 (`-p 8089:8089`)
- Kubernetes: update Helm values to expose port 8089

Co-authored-by: Madison Grubb <madison@elastiflow.com>
Reviewed-on: #6

server/utils/shutdown.js

@@ -0,0 +1,78 @@
+/**
+ * Graceful shutdown handler - registers cleanup functions and handles shutdown signals.
+ */
+
+import { SHUTDOWN_TIMEOUT_MS } from './constants.js'
+
+const cleanupFunctions = []
+const shutdownState = {
+  isShuttingDown: false,
+}
+
+export function clearCleanup() {
+  cleanupFunctions.length = 0
+  shutdownState.isShuttingDown = false
+}
+
+export function registerCleanup(fn) {
+  if (typeof fn !== 'function') throw new TypeError('Cleanup function must be a function')
+  cleanupFunctions.push(fn)
+}
+
+const executeCleanupFunction = async (fn, index) => {
+  try {
+    await fn()
+  }
+  catch (error) {
+    console.error(`[shutdown] Cleanup function ${index} failed:`, error?.message || String(error))
+  }
+}
+
+const executeCleanupReverse = async (functions, index = functions.length - 1) => {
+  if (index < 0) return
+  await executeCleanupFunction(functions[index], index)
+  return executeCleanupReverse(functions, index - 1)
+}
+
+async function executeCleanup() {
+  if (shutdownState.isShuttingDown) return
+  shutdownState.isShuttingDown = true
+  await executeCleanupReverse(cleanupFunctions)
+}
+
+export async function graceful(error) {
+  if (error) {
+    console.error('[shutdown] Shutting down due to error:', error?.message || String(error))
+    if (error.stack) console.error('[shutdown] Stack trace:', error.stack)
+  }
+  else {
+    console.log('[shutdown] Initiating graceful shutdown')
+  }
+  const timeout = setTimeout(() => {
+    console.error('[shutdown] Shutdown timeout exceeded, forcing exit')
+    process.exit(1)
+  }, SHUTDOWN_TIMEOUT_MS)
+  try {
+    await executeCleanup()
+    clearTimeout(timeout)
+    console.log('[shutdown] Cleanup complete')
+    process.exit(error ? 1 : 0)
+  }
+  catch (err) {
+    clearTimeout(timeout)
+    console.error('[shutdown] Error during cleanup:', err?.message || String(err))
+    process.exit(1)
+  }
+}
+
+export function initShutdownHandlers() {
+  for (const signal of ['SIGTERM', 'SIGINT']) {
+    process.on(signal, () => {
+      console.log(`[shutdown] Received ${signal}`)
+      graceful().catch((err) => {
+        console.error('[shutdown] Error in graceful shutdown:', err)
+        process.exit(1)
+      })
+    })
+  }
+}