Fix dangling tool terminalization in stream normalizer

[vutuanlinh2k2]

Summary

• prefer stable tool call IDs before transient part IDs in the shared stream normalizer
• terminalize dangling running tool parts during assistant finalization
• preserve prior tool state fields when terminal updates omit them

Tests

• pnpm exec vitest run tests/stream-normalizer.test.ts
• pnpm typecheck
• NODE_OPTIONS=--max-old-space-size=6144 pnpm build

Notes

• Full pnpm test hits existing local sandbox deferred-file failures on macOS shell/base64 behavior; the new stream-normalizer test passes both standalone and inside the full run.