store.max_retries configuration is ignored #82

Summary

The store.max_retries configuration value is not passed to object-store backends.

Current behavior

Backend construction ignores the configured retry count. The GCS implementation uses hard-coded retry limits instead, so operators cannot tune retry behavior and the documented setting has no runtime effect.

Expected behavior

Store operations should consistently use the configured retry budget, or the unsupported option should be removed.

Suggested implementation

Pass the validated retry value into backend constructors and use it in the shared retry policy for applicable operations. Add tests that use deterministic failures to verify the configured attempt count.

Relevant code

• crates/walgit-config/src/lib.rs:238
• crates/walgit-store/src/lib.rs:631
• crates/walgit-store/src/gcs.rs:33