feat(templates,campaigns): validate MITRE technique IDs, surface template suggestions first, manager can re-approve rejected campaigns

- TestTemplate/TemplateSuggestion creation and updates now reject any
  mitre_technique_id that doesn't match a real, already-synced MITRE
  ATT&CK technique. Frontend swaps the free-text ID input for a
  technique picker.
- Test Catalog now shows pending template suggestions before the
  catalog grid, with full field detail (platform, severity, tool,
  atomic ID, source URL, remediation) instead of just name/procedure.
- A manager can edit and directly re-approve a campaign they previously
  rejected, instead of needing the original lead to resubmit it.

frontend/src/components/CreateTemplateModal.tsx

@@ -1,8 +1,9 @@
 import { useState } from "react";
-import { useMutation, useQueryClient } from "@tanstack/react-query";
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { X, Loader2 } from "lucide-react";
 import { createTemplate, type CreateTemplatePayload } from "../api/test-templates";
 import { proposeTemplate } from "../api/template-suggestions";
+import { getTechniques, type TechniqueSummary } from "../api/techniques";
 import { useToast } from "./Toast";
 
 const SEVERITY_OPTIONS = ["low", "medium", "high", "critical"];
@@ -22,6 +23,11 @@ export default function CreateTemplateModal({
   const queryClient = useQueryClient();
   const { showToast } = useToast();
 
+  const { data: techniques, isLoading: techniquesLoading } = useQuery({
+    queryKey: ["techniques"],
+    queryFn: () => getTechniques(),
+  });
+
   const [form, setForm] = useState<CreateTemplatePayload>({
     mitre_technique_id: "",
     name: "",
@@ -91,15 +97,22 @@ export default function CreateTemplateModal({
           <div className="grid grid-cols-2 gap-4">
             <div>
               <label className="mb-1 block text-xs font-medium text-gray-500">
-                MITRE Technique ID <span className="text-red-400">*</span>
+                MITRE Technique <span className="text-red-400">*</span>
               </label>
-              <input
+              <select
                 required
+                disabled={techniquesLoading}
                 value={form.mitre_technique_id}
                 onChange={(e) => set("mitre_technique_id", e.target.value)}
-                placeholder="T1059.001"
                 className="w-full rounded-lg border border-gray-700 bg-gray-800 px-3 py-2 text-sm text-gray-200 focus:border-cyan-500 focus:outline-none"
-              />
+              >
+                <option value="">Select a technique</option>
+                {techniques?.map((tech: TechniqueSummary) => (
+                  <option key={tech.id} value={tech.mitre_id}>
+                    {tech.mitre_id} - {tech.name}
+                  </option>
+                ))}
+              </select>
             </div>
             <div>
               <label className="mb-1 block text-xs font-medium text-gray-500">