feat(attributes): Add browser.bfcache.* attributes

[logaretm]

Registers the four browser.bfcache.* attributes emitted by the new bfcacheMetricsIntegration in the JS SDK (getsentry/sentry-javascript#22397).

They describe browser back/forward-cache health metrics.

• browser.bfcache.outcome — hit/miss of a back/forward navigation.
• browser.bfcache.reason — a browser-reported not-restored reason (one per reason; a single miss can have several; Chromium-only via notRestoredReasons).
• browser.bfcache.frame — which frame the reason came from (top/child/masked/unknown).
• browser.bfcache.not_restored_reason_count — number of reported reasons (0 when the browser reported none, e.g. non-Chromium).

All are Sentry-specific, so is_in_otel: false and PII is not applicable here.

[github-actions]

Semver Impact of This PR

🟡 Minor (new features)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).

---

New Features ✨

Attributes

• Add browser.bfcache.* attributes by logaretm in #513

• Add Kafka messaging attributes by chargome in #474
• Deprecate rpc.grpc.status_code in favor of rpc.response.status_code by lucas-zimerman in #494
• Add deprecated messaging.destination_kind by andreiborza in #509
• Add sentry.segment.name.source attribute by Lms24 in #466
• Add attribute transformations by constantinius in #465
• Add stable app vitals attributes by buenaflor in #493
• Deprecate sentry.frames.* attributes by buenaflor in #500
• Add missing AI legacy aliases from Relay SpanData by vgrozdanic in #498

Other

• (conventions) Support multiple examples by Lms24 in #505

Internal Changes 🔧

Attributes

• Improve description of sentry.segment.name.source by Lms24 in #511
• Deprecate sentry.span.source and change backfill status of sentry.source by Lms24 in #510

Other

• (attribute) Improve db.statement example and add deprecation reason by Lms24 in #501
• (attrs) Backport attributes and normalizations from Relay by Dav1dde in #497
• (codeowners) Assign telemetry-experience to gen_ai/ai attributes by vgrozdanic in #506
• (release) Show version in workflow run title by constantinius in #504

---

_{🤖 This preview updates automatically when you update the PR.}