fix(cli): keep Ollama tool calls when stream deltas omit id

[seethinajayadileep]

Fixes #13225

Summary

Some providers (notably Ollama with models like gpt-oss) send the first streaming tool_calls delta with an index but no id. processToolCallDelta() only created an index→id mapping when id was present, so the first delta was dropped and later argument fragments never accumulated. Tool args then appeared as plain assistant text and the tool never ran.

Change

When a delta has index but no id and no mapping yet, synthesize a stable call_<index> id and store it in indexToIdMap so subsequent fragments attach correctly. Real provider ids are still preferred when present.

Test plan

• Unit tests for synthetic-id and real-id paths
• CLI agent turn with Ollama tool use: tool calls with index-only first deltas execute

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