fix(chat): document Google Chat Markdown formatting in tool descriptions

[kamladi]

Update chat.sendMessage and chat.sendDm tool descriptions to document Google Chat's supported text formatting syntax, helping LLMs generate properly formatted messages.

Partially addresses #58 (Chat formatting task).

Changes:

• Add CHAT_FORMATTING constant in src/utils/formatting/constants.ts
• Add CHAT_FORMATTING_SHORT for parameter descriptions
• Refactor tool descriptions to use shared constants

Testing:

• Manual test: LLM converts **bold** and __bold__ to *bold*
• Manual test: LLM converts *italic* to _italic_
• Manual test: LLM converts [text](url) to <url|text>
• Manual test: LLM flattens nested list items, but prefixes the list items with dashes to indicate depth (e.g., "- parent", "- -- child", "- --- grandchild")

Supported syntax:

- *bold* (single asterisks, not **)
- _italic_
- ~strikethrough~
- `inline code` and ```code blocks```
- Bulleted lists ("* " or "- " at line start)
- Links: <url|display text> (not [text](url))
- User mentions: <users/{user}>

Unsupported syntax (must be converted or avoided):

- **double asterisks** for bold
- # headings
- [text](url) markdown links
- > blockquotes

[gemini-code-assist]

Summary of Changes

Hello @kamladi, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the chat.sendMessage and chat.sendDm tools by embedding explicit documentation of Google Chat's unique Markdown formatting requirements directly into their descriptions. This change aims to guide Large Language Models (LLMs) in generating messages that adhere to Google Chat's syntax, thereby preventing formatting errors and improving the quality of automated communications.

Highlights

• New Formatting Constants: Introduced new constants CHAT_FORMATTING and CHAT_FORMATTING_SHORT to centralize Google Chat's specific Markdown formatting rules.
• Enhanced Tool Descriptions: Updated the chat.sendMessage and chat.sendDm tool descriptions to include detailed guidance on Google Chat's supported and unsupported text formatting, leveraging the new constants.
• LLM Guidance: Refactored tool descriptions to dynamically include formatting guidelines, ensuring Large Language Models (LLMs) generate properly formatted messages for Google Chat.

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[gemini-code-assist]

Code Review

This pull request effectively documents the Google Chat specific formatting for the chat.sendMessage and chat.sendDm tools by introducing shared constants. My review includes suggestions to make the formatting documentation even more complete by including all unsupported syntax mentioned in the PR description. I've also recommended a minor stylistic improvement to use template literals for better code readability.

[allenhutchison]

One question and one comment for you.

[allenhutchison]

Did you try adding these to the GEMINI-workspace.md file? It seems like a little overkill to add these to every tool description, but if you tried that and it didn't work I would understand why you took this route.

[allenhutchison]

We need a license header here to clear lint. If you run npm run lint:fix it should do the right thing.