Implement Batch File Operations: readManyFiles and writeManyFiles

[bsmi021]

Objective

Implement two new batch file operation capabilities in the server:

1. readManyFiles: Accepts a list of file names and returns their contents in a single request. This improves efficiency for LLMs and clients needing to load multiple files at once.
2. writeManyFiles: Accepts a JSON array of objects, each containing a file name and content, and writes all files in a single operation. This enables clients to quickly persist multiple files to disk without separate requests per file.

Requirements

• Expose both capabilities via the HTTP API and ensure documentation is updated accordingly.
• Ensure error handling for missing files (in readManyFiles) and write failures (in writeManyFiles) is robust and well-documented in responses.
• Provide example payloads and responses for both endpoints in the documentation.
• Unit and integration tests for both endpoints, including edge cases (e.g., partial failures).

Acceptance Criteria

• readManyFiles and writeManyFiles endpoints are available and documented.
• Batch operations are significantly more efficient than 1-by-1 file operations.
• Tests validate correct handling of normal and error cases.