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-tenant/src/otel/instruments.md

@@ -0,0 +1,83 @@
+# `instruments`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Lazily resolves the OpenTelemetry instruments (`Counter`, `Histogram`)
+the plugin emits from its production paths. The bundle is built on
+first call and cached; tests call `resetTenantPluginInstruments` after
+installing a fresh `MeterProvider` so subsequent calls rebind to the
+test exporter. This pattern lets the package work seamlessly in
+production (where the global provider is the OTel SDK) and under test
+(where the global provider is an `InMemoryMetricExporter`).
+
+## Features
+
+- Four instruments: `resolutionsTotal` (counter),
+  `resolutionDurationMs` (histogram), `cacheTotal` (counter),
+  `managementOpsTotal` (counter).
+- Lazy initialisation — the meter is resolved on first call so test
+  polyfills installed before the package loads bind correctly.
+- `resetTenantPluginInstruments` clears the cache so a re-bind is
+  forced; primarily useful in test setup hooks.
+
+## Usage: Basic Example
+
+```ts
+import { getTenantPluginInstruments } from "@suaveplan/api-plugin-tenant";
+
+const instruments = getTenantPluginInstruments();
+instruments.resolutionsTotal.add(1, { outcome: "resolved", strategy: "header" });
+instruments.resolutionDurationMs.record(12.4, { strategy: "header" });
+```
+
+## Usage: Advanced Example
+
+```ts
+import {
+    getTenantPluginInstruments,
+    resetTenantPluginInstruments,
+} from "@suaveplan/api-plugin-tenant";
+import { metrics } from "@opentelemetry/api";
+import { InMemoryMetricExporter, MeterProvider, PeriodicExportingMetricReader, AggregationTemporality } from "@opentelemetry/sdk-metrics";
+
+// In test setup before the package's other modules load:
+const exporter = new InMemoryMetricExporter(AggregationTemporality.CUMULATIVE);
+const reader = new PeriodicExportingMetricReader({ exporter, exportIntervalMillis: 60_000 });
+const provider = new MeterProvider({ readers: [reader] });
+metrics.setGlobalMeterProvider(provider);
+resetTenantPluginInstruments();
+
+// Later — assert the counters that were emitted:
+await provider.forceFlush();
+const collected = exporter.getMetrics();
+const resolutions = collected[0]?.scopeMetrics[0]?.metrics.find(
+    (m) => m.descriptor.name === "tenant_plugin.resolutions_total"
+);
+console.assert(resolutions !== undefined);
+```
+
+## API Reference
+
+- `interface TenantPluginInstruments` — `{ resolutionsTotal: Counter,
+  resolutionDurationMs: Histogram, cacheTotal: Counter,
+  managementOpsTotal: Counter }`.
+- `function getTenantPluginInstruments(): TenantPluginInstruments` —
+  returns the cached bundle, building it on first call.
+- `function resetTenantPluginInstruments(): void` — drops the cache.
+
+## Implementation Notes
+
+The lazy pattern is essential — calling `metrics.getMeter("...")` at
+module top-level binds to whichever `MeterProvider` was installed at
+import time. Because Vitest's `setupFiles` run before `src/` modules
+import, installing the in-memory provider there guarantees the test
+bundle binds correctly. Production callers that install their OTel SDK
+late (e.g. behind a feature flag) call `resetTenantPluginInstruments`
+once the SDK is up so the plugin rebinds. The instrument names use
+`tenant_plugin.` rather than `tenant.` so dashboards can cleanly
+distinguish the plugin's emissions from the underlying
+`@suaveplan/api-tenant` library's instruments (if any are added later).