Add an experimental doc as a repository for AI agent knowledge (#1734)

* Create Jules.md AI guide and incorporate feedback

This commit introduces the Jules.md file, a comprehensive guide for AI agents
contributing to the Firebase C++ SDK.

The document covers:
- Repository setup and build commands for various platforms.
- Testing strategy, emphasizing integration tests.
- Overview of the API surface, including initialization, Futures, core class patterns (using Auth and Database as examples), and listeners.
- Best practices for coding style, error handling, resource management, and platform-specific code.
- Common coding patterns observed in the repository like Pimpl, namespace usage, and platform abstraction.
- A section on how to prompt AI agents effectively when working with this codebase, including suggested prompt text and key directives.
- A reminder to keep Jules.md updated with new patterns.

This addresses your initial request to create a context document for AI agents
and incorporates your feedback to:
- Generalize API examples previously focused on Firestore.
- Add a new section with guidance for prompting AI agents.

* Formatted Jules.md to 80-character line wrap

This commit reformats the Jules.md AI guide to ensure all narrative
text is wrapped to a maximum of 80 characters per line.

This change improves readability, especially in environments or editors
with limited horizontal space, and aligns with common markdown style
preferences. Code blocks have been preserved with minimal changes
to maintain their integrity.

* Enrich Jules.md with info from online Firebase C++ docs

This commit updates Jules.md, the AI agent guide, with additional
context and details sourced from the official Firebase C++ online
documentation.

Key enhancements include:

-   **Introduction**: Added a link to the Firebase library support by
    platform table and a note on the open-source structure of the C++ SDKs
    (desktop vs. mobile).
-   **Setup Commands**:
    -   Clarified iOS setup to include linking .framework files alongside
        pods.
    -   Added a new "Desktop Platform Setup Details" subsection, covering:
        -   Conversion of iOS `GoogleService-Info.plist` to
            `google-services-desktop.json` using the provided Python
            script.
        -   Search order for desktop configuration files.
        -   Common system library dependencies for Windows, macOS, and
            Linux desktop builds.
-   **API Surface**:
    -   Clarified that `firebase::auth::User` objects are typically
        obtained from `firebase::auth::AuthResult` after successful
        authentication operations.
-   **Best Practices**:
    -   Added a "Platform-Specific Considerations" subsection detailing:
        -   The REST-based nature of the Realtime Database C++ SDK on
            desktop and the consequent need for server-side indexing for
            `OrderByChild()` queries.
        -   Awareness of iOS method swizzling used by some Firebase
            products.

These additions provide more comprehensive guidance for you,
particularly regarding platform-specific nuances and SDK architecture.
The document maintains an 80-character line wrap.

* I've updated the Jules.md file with information about Analytics initialization and Future management.

This update incorporates further feedback from you into Jules.md:

1.  **Clarified Analytics Initialization:**
    The "API Surface" -> "Initialization" section now specifies that
    Firebase Analytics uses a different initialization pattern
    (`firebase::analytics::Initialize(app)`) compared to the common
    `GetInstance(app, ...)` pattern of other services. It also notes
    that Analytics functions are typically called globally.

2.  **Added Future Lifecycle Management Guidance:**
    A new point in "Best Practices" -> "Resource Management" emphasizes
    the importance of ensuring `Future` objects complete their course
    (e.g., via `OnCompletion` or by checking results) to prevent
    potential issues with operations not finalizing or resources not
    being cleaned up promptly.

These changes provide more nuanced guidance for interacting with the Firebase C++ SDK.

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Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: jonsimantov