Move docs/ package mirror into document-navigator plugin

Relocate the ~6k-file docs tree from the repo root into
plugins/document-navigator/docs/ so the plugin is self-contained and
portable. docs/superpowers/ (specs and plans) stays at the repo root.

Moved via cp+rm rather than git mv because directory rename() fails with
EPERM on this WSL /mnt DrvFs mount; git rename-detection pairs the
identical-content files at commit time.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/document-navigator/docs/api-stack/api/api-plugin-webhook/src/otel/instruments.md

@@ -0,0 +1,65 @@
+# `instruments.ts` — webhook plugin OpenTelemetry instruments
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Defines the four OpenTelemetry instruments emitted by the webhook plugin: two counters and two histograms covering every observable outcome of `WebhookService.send`. The bundle is lazily built against the process-wide `MeterProvider` and cached so repeat calls return the same `Counter` / `Histogram` references — this means tests can install a fresh provider, call `resetWebhookInstruments()`, and trust that the next `getWebhookInstruments()` rebinds against it. Without this seam, tests that install a `MeterProvider` after the first import see metrics flow to a stale meter and silently drop observations.
+
+## Features
+
+- Four instruments — `deliveries_total`, `dead_letters_total`, `delivery_attempts`, `send_duration_ms`.
+- Lazy + cached binding so the meter is resolved on first read, not at import time.
+- `resetWebhookInstruments()` for test isolation.
+- Stable namespace `webhook_plugin.*` to keep the plugin's metrics separate from `@suaveplan/webhook-client`'s `webhook_client.*` metrics.
+
+## Usage: Basic
+
+```ts
+import { getWebhookInstruments } from "@suaveplan/api-plugin-webhook/otel/instruments";
+
+const inst = getWebhookInstruments();
+inst.deliveriesTotal.add(1, { event: "order.created", status: "delivered" });
+```
+
+## Usage: Advanced
+
+```ts
+// Tests typically install a fresh MeterProvider, then call resetWebhookInstruments
+// so the next getWebhookInstruments() rebinds against the freshly-installed provider.
+
+import { metrics } from "@opentelemetry/api";
+import {
+    AggregationTemporality,
+    InMemoryMetricExporter,
+    MeterProvider,
+    PeriodicExportingMetricReader,
+} from "@opentelemetry/sdk-metrics";
+import {
+    getWebhookInstruments,
+    resetWebhookInstruments,
+} from "@suaveplan/api-plugin-webhook/otel/instruments";
+
+const exporter = new InMemoryMetricExporter(AggregationTemporality.CUMULATIVE);
+const reader = new PeriodicExportingMetricReader({ exporter, exportIntervalMillis: 60_000 });
+const provider = new MeterProvider({ readers: [reader] });
+metrics.setGlobalMeterProvider(provider);
+resetWebhookInstruments();
+
+const inst = getWebhookInstruments();
+inst.deliveriesTotal.add(1, { event: "evt", status: "delivered" });
+await provider.forceFlush();
+console.log(exporter.getMetrics());
+```
+
+## API Reference
+
+- `getWebhookInstruments()` — returns the cached `WebhookInstruments` bundle, lazily binding on first call.
+- `resetWebhookInstruments()` — drops the cache so the next `getWebhookInstruments()` rebinds.
+- `WebhookInstruments` — `{ deliveriesTotal, deadLettersTotal, deliveryAttempts, sendDurationMs }`.
+
+## Implementation Notes
+
+The namespace `webhook_plugin.*` was chosen explicitly so dashboards and alerts can distinguish plugin-level emissions from the `webhook_client.*` emissions the underlying delivery library emits. The label set `{event, status, endpoint_id}` on `deliveries_total` deliberately includes `endpoint_id` even though it has unbounded cardinality — operators with many endpoints SHOULD aggregate at scrape time using a recording rule that drops the label. Including it at emission time means operators can debug a single endpoint without recompiling. The histograms inherit OTel's default bucket layout (no custom `boundaries` supplied) — operators tune via SDK views, not by editing this file.