Add tests and implement StubBearer authentication for Signer endpoints

- Created SignerEndpointsTests to validate the SignDsse and VerifyReferrers endpoints.
- Implemented StubBearerAuthenticationDefaults and StubBearerAuthenticationHandler for token-based authentication.
- Developed ConcelierExporterClient for managing Trivy DB settings and export operations.
- Added TrivyDbSettingsPageComponent for UI interactions with Trivy DB settings, including form handling and export triggering.
- Implemented styles and HTML structure for Trivy DB settings page.
- Created NotifySmokeCheck tool for validating Redis event streams and Notify deliveries.

scripts/verify-notify-plugins.sh

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+plugins_dir="${repo_root}/plugins/notify"
+
+declare -A assemblies=(
+  [slack]="StellaOps.Notify.Connectors.Slack.dll"
+  [teams]="StellaOps.Notify.Connectors.Teams.dll"
+  [email]="StellaOps.Notify.Connectors.Email.dll"
+  [webhook]="StellaOps.Notify.Connectors.Webhook.dll"
+)
+
+status=0
+
+for channel in "${!assemblies[@]}"; do
+  dir="${plugins_dir}/${channel}"
+  if [[ ! -d "${dir}" ]]; then
+    echo "ERROR: Missing plug-in directory '${dir}'."
+    status=1
+    continue
+  fi
+
+  manifest="${dir}/notify-plugin.json"
+  assembly="${dir}/${assemblies[$channel]}"
+  base="${assemblies[$channel]%.dll}"
+  pdb="${dir}/${base}.pdb"
+  deps="${dir}/${base}.deps.json"
+
+  if [[ ! -f "${manifest}" ]]; then
+    echo "ERROR: Missing manifest for '${channel}' connector (${manifest})."
+    status=1
+  fi
+
+  if [[ ! -f "${assembly}" ]]; then
+    echo "ERROR: Missing assembly for '${channel}' connector (${assembly})."
+    status=1
+  fi
+
+  while IFS= read -r -d '' file; do
+    name="$(basename "${file}")"
+    case "${name}" in
+      "notify-plugin.json" \
+        | "${assemblies[$channel]}" \
+        | "${base}.pdb" \
+        | "${base}.deps.json")
+        ;;
+      *)
+        echo "ERROR: Unexpected file '${name}' in '${dir}'."
+        status=1
+        ;;
+    esac
+  done < <(find "${dir}" -maxdepth 1 -type f -print0)
+done
+
+exit "${status}"