refactor: rename fields, methods, and vars related to RetryBackoff

[quettabit]

addresses #254

[greptile-apps]

Greptile Overview

Greptile Summary

Renamed fields, methods, and variables related to RetryBackoff for improved semantic clarity and consistency across the codebase.

Key changes:

• RetryBackoff struct fields: max_attempts → max_retries, cur_attempt → cur_retry
• Method: attempts_used() → used()
• Variables: retry_backoffs (plural) → retry_backoff (singular) in api.rs, session/append.rs, and session/read.rs

The refactoring improves naming consistency since the struct deals with retries, not attempts. All usages were updated correctly, including test cases.

Confidence Score: 5/5

• This PR is safe to merge with no risk
• Pure refactoring with consistent naming changes across all files. No logic changes, all tests updated correctly, and the semantic naming is more accurate
• No files require special attention

Important Files Changed

Filename	Overview
src/retry.rs	Renamed fields from max_attempts/cur_attempt to max_retries/cur_retry and method attempts_used() to used() for better semantic consistency
src/api.rs	Renamed variable retry_backoffs to retry_backoff (singular) for better clarity
src/session/append.rs	Renamed variable retry_backoffs to retry_backoff (singular) for consistency
src/session/read.rs	Renamed variable retry_backoffs to retry_backoff (singular) and updated call to used() method

_{Last reviewed commit: c06284e}