GOOSE_CLI_SHOW_THINKING not working for DeepSeek model through OpenRouter

**Describe the bug**

As the title says, after setting GOOSE_CLI_SHOW_THINKING=1 and then starting a session with DeepSeek V4 Flash 0731 (through OpenRouter), I do not see the thinking tokens in the CLI. I confirmed that the this model exposes reasoning tokens as navigating to the same session in the Goose Desktop App shows the "thinking" toggle which when clicked shows the reasoning tokens that are missing in the CLI.

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**To Reproduce**
Steps to reproduce the behavior:
1. Start TTY and do export GOOSE_CLI_SHOW_THINKING=1
2. (Optional) goose configure in terminal and set your provider and model to open router -> DeepSeek V4 Flash 0731
3. Run goose session in the terminal and ask a question

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**Expected behavior**

I should be able to see the same tokens that I see in the GUI in the terminal as well.

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**Please provide the following information**
- **OS & Arch:** Fedora 44
- **Interface:** CLI
- **Version:** 1.45
- **Extensions enabled:** None
- **Provider & Model:** DeepSeek V4 Flash 0731 (through OpenRouter)

Look for the CLI output handling code, likely in a module like `cli/src/output.rs` or `cli/src/session.rs`. Search for the environment variable `GOOSE_CLI_SHOW_THINKING` and how it controls the display of reasoning tokens. Compare the CLI's token handling with the desktop app's implementation to see where the DeepSeek/OpenRouter stream parsing differs. Run the CLI with debugging to trace the token flow.

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