docs(cloud_firestore): explain Isolates usage patterns

[enesbugrahankilic]

Summary

• Adds a Using Cloud Firestore with Isolates section to the cloud_firestore README
• Explains platform-channel / main-isolate limitation
• Shows the recommended pattern: fetch on main isolate → send plain Map/List data → process in Isolate.run / compute
• Links related issues

Fixes #9518

Note: Official firebase.google.com Firestore Flutter pages live outside this repo (snippets-only). Package README is a practical place for this guidance until site docs can mirror it.

Test plan

• Read the new README section for clarity
• Confirm linked issue numbers are correct

[gemini-code-assist]

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize the Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counterproductive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for GitHub and other Google products, sign up here.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[enesbugrahankilic]

Signed the Google CLA — please re-check when convenient.

[enesbugrahankilic]

Updated Google Individual CLA with eneskilicresmi@gmail.com and GitHub username enesbugrahankilic — please re-check.

[enesbugrahankilic]

I signed it!