SMOODEV-2706: Add installWebVitals RUM one-liner to browser SDK

[brentrager]

Problem

Customers embedding the @smooai/observability browser SDK have no turnkey way to report Core Web Vitals. They'd have to wire web-vitals callbacks to a MetricsClient themselves and get the metric names/attrs right by hand.

Solution

Add installWebVitals(metrics, opts?) to @smooai/observability/browser — a one-liner that records Core Web Vitals against the existing browser MetricsClient:

import { getMetricsClient } from '@smooai/observability/metrics';
import { installWebVitals } from '@smooai/observability/browser';

installWebVitals(getMetricsClient('my-web-app'));

Pinned metric contract (matches the apps/web RUM dogfood exactly):

• web.vitals.lcp / .fcp / .inp / .ttfb — histogram, unit ms (via MetricsClient.timing)
• web.vitals.cls — histogram, unitless raw CLS (via MetricsClient.histogram)
• attributes on every point: route (location.pathname, overridable via opts.route for SPA routers), rating (good|needs-improvement|poor), navigation_type (metric.navigationType)

Details:

• Browser-guarded — no-op during SSR (typeof window === 'undefined').
• Idempotent — repeat calls are a no-op (won't double-register PerformanceObservers).
• Lazy — web-vitals is dynamically imported only when installWebVitals is called, so it stays out of the critical path and off the node/SSR bundle.
• No dependency on any product internals.
• web-vitals@^5.3.0 added as a dependency (tiny, no transitive deps).
• No metrics catalog exists in this SDK to register against (searched all langs) — nothing to add there.

Verification

• pnpm --filter @smooai/observability test — 62 pass (3 new, driving recordWebVital with a fake MetricsClient + synthetic metrics; asserts exact name / recording kind / attrs for each vital).
• pnpm --filter @smooai/observability typecheck — clean.
• pnpm --filter @smooai/observability build — clean; confirmed installWebVitals/recordWebVital exported from dist/browser.mjs + browser.d.mts, and import("web-vitals") stays a lazy runtime import (not bundled).

Release

⚠️ Hold for release until the logs signal ships — changeset included (minor), but do NOT publish this ahead of the logs signal. Release the two together.

🤖 Generated with Claude Code

https://claude.ai/code/session_01S2bM94GAnVjYSSv1x7HKRB

[changeset-bot]

🦋 Changeset detected

Latest commit: d4b8474

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@smooai/observability	Minor

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[brentrager]

Standing down — premise was false: the browser SDK has no metrics transport (getMetricsClient is a Node-only OTel no-op in the browser), so installWebVitals would silently send nothing. Real prerequisite is a browser metrics transport (extend the error transport's IngestPayload with type:'metric'), deferred to the customer-release phase (pearl th-e67905) after dogfooding the path inside the monorepo. Branch left on remote for reference; not deleting since it'll inform th-e67905.