fix(ai): preserve Anthropic server tool replay

[code-yeongyu]

Summary

Fix Anthropic same-model replay for assistant messages that contain provider-native server tool blocks and signed thinking.

The failing session 019ed4f0-2914-701d-9614-dd0f58c0b103 ended with Anthropic rejecting the next request because thinking blocks had been modified. The local replay serializer preserved signed thinking text, but it dropped same-model Anthropic providerNative blocks such as server_tool_use and web_search_tool_result. That changed the protected assistant content sequence before the follow-up tool-result request.

This patch keeps replayable Anthropic provider-native raw blocks only for the same provider/api/model, while continuing to drop non-portable cross-provider native blocks.

QA Evidence

Evidence directory: local-ignore/qa-evidence/20260617-thinking-session-fix/

• Failing-first: red-anthropic-provider-native.txt showed same-model provider-native server blocks were dropped from the Anthropic replay payload.
• Regression: green-anthropic-provider-native-replay-after-review.txt passed test/anthropic-provider-native-replay.test.ts with the real failure shape: server native blocks + signed thinking + text + tool call + tool result.
• Focused hermetic suite: green-focused-ai-tests-hermetic.txt passed 13 tests with 1 live Anthropic E2E skipped.
• Full check: npm-run-check-after-install.txt passed npm run check after npm install --ignore-scripts hydrated already-declared local @types packages.
• Senpi real CLI QA: senpi-qa-mock-loop-anthropic-self.txt and senpi-qa-mock-loop-anthropic-tool.txt passed the Anthropic mock loop and multi-turn tool loop with zero real provider calls and real auth unchanged.
• Review: ultrawork reviewer approval recorded after the regression test was staged.

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Summary by cubic

Fixes Anthropic same-model replay to keep server-native tool blocks around signed thinking so follow-up tool-result requests are accepted. Restores stable multi-turn tool flows and scopes PR530 benchmark suites by package for faster CI.

• Bug Fixes
  • Preserve a whitelist of Anthropic provider-native blocks when replaying the same provider/api/model (e.g., server_tool_use, web_search_tool_result); continue dropping cross-provider native blocks.
  • Added a regression test to verify signed thinking + native server blocks + tool use replay; removed the obsolete test that expected provider-native blocks to be dropped.

^{Written for commit 856288b. Summary will update on new commits.}