fix(doctor): preserve legacy Claude CLI runtime intent

[steipete]

Summary

• Preserve recoverable legacy whole-agent Claude CLI runtime pins by moving matching selected Anthropic models to model-scoped runtime policy before stale pins are removed.
• Cover compatibility normalization and actual legacy doctor --fix migration, while preserving explicit per-model runtime overrides.
• Add changelog entry for 2026.5.12: WhatsApp runtime silently rebinds, agent loses all tools #83491.

Verification

• node scripts/run-vitest.mjs src/commands/doctor-legacy-config.migrations.test.ts src/commands/doctor/shared/legacy-config-migrate.test.ts
• git diff --check
• pnpm check:changed (Blacksmith Testbox tbx_01krxrhxvn9s0hdgx5b8evqq52, provider blacksmith-testbox, exit 0)
• AUTOREVIEW_AUTO_TESTS=0 .agents/skills/autoreview/scripts/autoreview --mode local (fallback reviewer after Codex local parser quirk, clean)
• AUTOREVIEW_AUTO_TESTS=0 .agents/skills/autoreview/scripts/autoreview --mode commit --commit HEAD (clean)

Behavior addressed: openclaw doctor --fix now preserves a recoverable legacy whole-agent Claude CLI runtime pin by writing matching Anthropic model runtime policy before deleting the stale pin.
Real environment tested: local focused Vitest plus Blacksmith Testbox changed gate.
Exact steps or command run after this patch: node scripts/run-vitest.mjs src/commands/doctor-legacy-config.migrations.test.ts src/commands/doctor/shared/legacy-config-migrate.test.ts; pnpm check:changed.
Evidence after fix: focused tests pass and Testbox tbx_01krxrhxvn9s0hdgx5b8evqq52 exits 0.
Observed result after fix: doctor migration emits model-scoped agentRuntime entries for matching Anthropic models and does not overwrite explicit pi runtime entries.
What was not tested: live WhatsApp/package-upgrade reproduction; this patch covers config/doctor migration behavior only.

Fixes #83491