feat(exec-dashboard): vertical bars for Coverage by Tactic in MITRE order

- Convert horizontal bar chart to vertical bars (columns)
- Sort all 14 MITRE ATT&CK tactics in official order:
  Reconnaissance → Resource Development → Initial Access → Execution →
  Persistence → Privilege Escalation → Defense Evasion → Credential Access →
  Discovery → Lateral Movement → Collection → C2 → Exfiltration → Impact
- Show ALL tactics (not a subset)
- Labels rotated -45° to fit all names
- Bars have rounded top corners; horizontal gridlines only

frontend/src/pages/ExecutiveDashboardPage.tsx

@@ -232,14 +232,39 @@ export default function ExecutiveDashboardPage() {
     })
     .slice(0, 10);
 
-  // Coverage by tactic for bar chart
-  const tacticData = (tacticCoverage || []).map((tc) => ({
-    name: tc.tactic
-      .split("-")
-      .map((w: string) => w.charAt(0).toUpperCase() + w.slice(1))
-      .join(" "),
-    coverage: tc.total > 0 ? Math.round(((tc.validated + tc.partial) / tc.total) * 100) : 0,
-  }));
+  // Official MITRE ATT&CK tactic order (slug → display label)
+  const MITRE_TACTIC_ORDER: Record<string, string> = {
+    "reconnaissance":         "Reconnaissance",
+    "resource-development":   "Resource Development",
+    "initial-access":         "Initial Access",
+    "execution":              "Execution",
+    "persistence":            "Persistence",
+    "privilege-escalation":   "Privilege Escalation",
+    "defense-evasion":        "Defense Evasion",
+    "credential-access":      "Credential Access",
+    "discovery":              "Discovery",
+    "lateral-movement":       "Lateral Movement",
+    "collection":             "Collection",
+    "command-and-control":    "C2",
+    "exfiltration":           "Exfiltration",
+    "impact":                 "Impact",
+  };
+
+  const tacticDataRaw = (tacticCoverage || []).map((tc) => {
+    const slug = tc.tactic.toLowerCase();
+    const label = MITRE_TACTIC_ORDER[slug] ||
+      tc.tactic.split("-").map((w: string) => w.charAt(0).toUpperCase() + w.slice(1)).join(" ");
+    const order = Object.keys(MITRE_TACTIC_ORDER).indexOf(slug);
+    return {
+      name: label,
+      slug,
+      order: order === -1 ? 99 : order,
+      coverage: tc.total > 0 ? Math.round(((tc.validated + tc.partial) / tc.total) * 100) : 0,
+    };
+  });
+
+  // Sort by official MITRE order; include any unknown tactics at end
+  const tacticData = tacticDataRaw.sort((a, b) => a.order - b.order);
 
   const getBarColor = (coverage: number) => {
     if (coverage < 30) return "#ef4444";
@@ -512,24 +537,25 @@ export default function ExecutiveDashboardPage() {
           Coverage by Tactic
           <MetricTooltip title="Coverage by Tactic" description="How well each MITRE ATT&CK tactic (attack phase) is covered by validated tests. Tactics represent different stages of an attack, from Initial Access to Impact." context="Red bars (low coverage) are highest priority. Focus testing on those tactics first." />
         </h2>
-        <ResponsiveContainer width="100%" height={300}>
+        <ResponsiveContainer width="100%" height={260}>
           <BarChart
             data={tacticData}
-            layout="vertical"
-            margin={{ left: 120 }}
+            margin={{ top: 8, right: 8, bottom: 64, left: 8 }}
+            barCategoryGap="20%"
           >
-            <CartesianGrid strokeDasharray="3 3" stroke="#1f2937" />
+            <CartesianGrid strokeDasharray="3 3" stroke="#1f2937" vertical={false} />
             <XAxis
-              type="number"
+              dataKey="name"
+              tick={{ fill: "#9ca3af", fontSize: 10 }}
+              angle={-45}
+              textAnchor="end"
+              interval={0}
+            />
+            <YAxis
               domain={[0, 100]}
               tick={{ fill: "#6b7280", fontSize: 10 }}
               tickFormatter={(v) => `${v}%`}
-            />
-            <YAxis
-              type="category"
-              dataKey="name"
-              width={120}
-              tick={{ fill: "#9ca3af", fontSize: 10 }}
+              width={36}
             />
             <Tooltip
               contentStyle={{
@@ -540,7 +566,7 @@ export default function ExecutiveDashboardPage() {
               }}
               formatter={(value: number) => [`${value}%`, "Coverage"]}
             />
-            <Bar dataKey="coverage" radius={[0, 4, 4, 0]}>
+            <Bar dataKey="coverage" radius={[4, 4, 0, 0]}>
               {tacticData.map((entry, index) => (
                 <Cell
                   key={`cell-${index}`}