fix: docs-exempt + de-dup PR ref on sonnet-5 changeset (adversarial findings)

- Added-type fragment needs docs or a docs-exempt marker (lint-docs-required);
  Sonnet 5 operator docs already landed on next via #1851 → docs-exempt.
- Serializer auto-appends (#pr); drop the manual (#1848) from the body so it
  doesn't render (#1847) (#1848) (#1848). Keep the #1847 issue ref inline.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.changeset/1847-claude-sonnet-5-standard-tier.md

@@ -2,4 +2,6 @@
 type: Added
 pr: 1848
 ---
-**Claude Sonnet 5 is now the `standard` (sonnet) tier model.** The model catalog and provider presets resolve the sonnet/standard tier to `claude-sonnet-5` (GA 2026-06-30) across the Anthropic-backed runtimes (`claude`, `copilot`, and the `anthropic`/`anthropic-fable` presets), plus the OpenRouter-style `anthropic/claude-sonnet-5` for `opencode`/`hermes`, replacing the superseded `claude-sonnet-4-6`. Opus and Haiku tier defaults are unchanged (the `haiku` high-effort preset's escalation slot tracks the current sonnet model). Shipped in 1.6.1. (#1847) (#1848)
+**Claude Sonnet 5 is now the `standard` (sonnet) tier model.** The model catalog and provider presets resolve the sonnet/standard tier to `claude-sonnet-5` (GA 2026-06-30) across the Anthropic-backed runtimes (`claude`, `copilot`, and the `anthropic`/`anthropic-fable` presets), plus the OpenRouter-style `anthropic/claude-sonnet-5` for `opencode`/`hermes`, replacing the superseded `claude-sonnet-4-6`. Opus and Haiku tier defaults are unchanged (the `haiku` high-effort preset's escalation slot tracks the current sonnet model). Shipped in 1.6.1. (#1847)
+
+<!-- docs-exempt: Sonnet 5 operator docs (CONFIGURATION.md model-tier tables, settings-advanced.md) already landed on next via #1851; this fragment only records the already-shipped 1.6.1 change so the 1.7.0 changelog render reflects current shipping code. -->