fix(agent): recover tools after stream parse errors

[usr-bin-roygbiv]

What

• recover completed registered tool calls after explicit transient stream JSON parse failures
• drop incomplete calls and keep unknown, refused, sensitive, and non-stream error turns non-executable
• classify persisted parser diagnostics narrowly without weakening provider-context Error classification

Why

OpenAI Responses can complete a tool call and then emit a malformed non-trailing SSE event. OMP 17.0.5 surfaced JSON Parse error: Unterminated string, but the agent loop only recovered completed calls for stream_read_error, so the completed tool never executed. The same failure shape was observed independently on macOS and Linux sessions.

Testing

• bun test packages/agent/test/agent-loop.test.ts packages/agent/test/agent.test.ts packages/ai/test/error-aierr.test.ts packages/ai/test/anthropic-retry.test.ts — 125 pass
• bun check — pass
• bun run ci:test:smoke — pass
• deterministic source-CLI smoke in cmux on macOS — completed read, malformed middle SSE JSON frame, recovered tool result, continued to OMP_MIDSTREAM_FINAL_LOCAL_OK
• deterministic source-CLI smoke in native tmux on Linux — same sequence, continued to OMP_MIDSTREAM_FINAL_REMOTE_OK

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• bun check passes
• Tested locally
• CHANGELOG updated (if user-facing)