feat(voyage): wire Stop event to otel-export.mjs in hooks.json

Step 13 of v4.1 — adds Stop hook entry pointing to
hooks/scripts/otel-export.mjs (added in Step 12 / commit c5fb745).
Mounts the orchestrator on Claude Code's Stop event so OTel/Prometheus
export runs at session-end when VOYAGE_EXPORT_MODE is set.

HIGH-risk-mitigering: tests/hooks/hooks-json-stop-wired.test.mjs
asserter at Stop-key finnes, refererer otel-export.mjs, bruker
\${CLAUDE_PLUGIN_ROOT}-substitusjon, og har type:command.

Tests: 464 → 468 (4 new). All green.

plugins/voyage/hooks/hooks.json

@@ -60,6 +60,16 @@
           }
         ]
       }
+    ],
+    "Stop": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "node ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/otel-export.mjs"
+          }
+        ]
+      }
     ]
   }
 }

plugins/voyage/tests/hooks/hooks-json-stop-wired.test.mjs

@@ -0,0 +1,65 @@
+// SC-13: hooks.json wires Stop event to otel-export.mjs
+// HIGH-risk-mitigering — verify deterministic config-pinning (mønster fra
+// tests/lib/doc-consistency.test.mjs).
+
+import { test } from 'node:test';
+import { strict as assert } from 'node:assert';
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, resolve } from 'node:path';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const HOOKS_JSON_PATH = resolve(__dirname, '../../hooks/hooks.json');
+
+function loadHooksJson() {
+  const raw = readFileSync(HOOKS_JSON_PATH, 'utf8');
+  return JSON.parse(raw);
+}
+
+test('hooks.json — Stop key exists with at least one entry', () => {
+  const cfg = loadHooksJson();
+  assert.ok(cfg.hooks, 'hooks.json mangler top-level "hooks" object');
+  assert.ok(Array.isArray(cfg.hooks.Stop), 'hooks.json mangler "Stop" array');
+  assert.ok(cfg.hooks.Stop.length >= 1, 'Stop array er tom — forventet ≥1 entry');
+});
+
+test('hooks.json — Stop entry refererer otel-export.mjs', () => {
+  const cfg = loadHooksJson();
+  const stopEntries = cfg.hooks.Stop;
+  const allCommands = stopEntries.flatMap((entry) =>
+    (entry.hooks || []).map((h) => h.command || ''),
+  );
+  const hasOtelExport = allCommands.some((cmd) => cmd.includes('otel-export.mjs'));
+  assert.ok(
+    hasOtelExport,
+    `ingen Stop-hook refererer otel-export.mjs. Funnet: ${JSON.stringify(allCommands)}`,
+  );
+});
+
+test('hooks.json — Stop entry bruker ${CLAUDE_PLUGIN_ROOT}-substitusjon', () => {
+  const cfg = loadHooksJson();
+  const stopEntries = cfg.hooks.Stop;
+  const otelEntry = stopEntries
+    .flatMap((entry) => entry.hooks || [])
+    .find((h) => (h.command || '').includes('otel-export.mjs'));
+  assert.ok(otelEntry, 'fant ikke otel-export-entry i Stop');
+  assert.match(
+    otelEntry.command,
+    /\$\{CLAUDE_PLUGIN_ROOT\}/,
+    'otel-export-command bruker ikke ${CLAUDE_PLUGIN_ROOT}-prefix — relative paths feiler i headless',
+  );
+  assert.match(
+    otelEntry.command,
+    /^node\s+/,
+    'otel-export-command starter ikke med "node " — invocation-form ikke korrekt',
+  );
+});
+
+test('hooks.json — Stop entry har "type": "command"', () => {
+  const cfg = loadHooksJson();
+  const stopEntries = cfg.hooks.Stop;
+  const otelHook = stopEntries
+    .flatMap((entry) => entry.hooks || [])
+    .find((h) => (h.command || '').includes('otel-export.mjs'));
+  assert.equal(otelHook.type, 'command', 'otel-export-hook mangler "type": "command"');
+});