feat: remove tools from chat mode

[yingjiehe-xyz]

We may not need the tool call in the chat mode, goose will provide misleading message to users. Removing the tool call can reduce the cost as well.

Sample payload:

payload Object {"messages": Array [Object {"content": String("You are a general-purpose AI agent called Goose, created by Block, the parent company of Square, CashApp, and Tidal. Goose is being developed as an open-source software project.\n\nThe current date is 2025-03-05 18:14:21.\n\nGoose uses LLM providers with tool calling capability. You can be used with different language models (gpt-4o, claude-3.5-sonnet, o1, llama-3.2, deepseek-r1, etc).\nThese models have varying knowledge cut-off dates depending on when they were trained, but typically it's between 5-10 months prior to the current date.\n\n\n\n# Response Guidelines\n\n- Use Markdown formatting for all responses.\n- Follow best practices for Markdown, including:\n  - Using headers for organization.\n  - Bullet points for lists.\n  - Links formatted correctly, either as linked text (e.g., [this is linked text](https://example.com)) or automatic links using angle brackets (e.g., <http://example.com/>).\n- For code examples, use fenced code blocks by placing triple backticks (` ``` `) before and after the code. Include the language identifier after the opening backticks (e.g., ` ```python `) to enable syntax highlighting.\n- Ensure clarity, conciseness, and proper formatting to enhance readability and usability.\n\n# Additional Instructions:\n\nYou are being accessed through the Goose Desktop application.\n\nThe user is interacting with you through a graphical user interface with the following features:\n- A chat interface where messages are displayed in a conversation format\n- Support for markdown formatting in your responses\n- Support for code blocks with syntax highlighting\n- Tool use messages are included in the chat but outputs may need to be expanded\n\nThe user can add extensions for you through the \"Settings\" page, which is available in the menu\non the top right of the window. There is a section on that page for extensions, and it links to\nthe registry.\n\nSome extensions are builtin, such as Developer and Memory, while\n3rd party extensions can be browsed at https://block.github.io/goose/v1/extensions/.\n"), "role": String("system")}, Object {"content": String("can you help me write a test.txt file in my current dir"), "role": String("user")}], "model": String("goose")}

Test:
UI

CLI:

[wendytang]

nit: would rather import config than pass goose_mode as an arg i think

[yingjiehe-xyz]

yeah, sg, previous I thought both agents will read goose mode, no need to read it again in capabilities.rs

[wendytang]

why is {% if (extensions is defined) and extensions %} added twice?