feat(seatbelt): introduce config for each middleware

[martintmk]

Resolves #301

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.0%. Comparing base (7bf2cb4) to head (a9065aa).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #302   +/-   ##
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  Coverage   100.0%   100.0%           
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  Files         144      147    +3     
  Lines        8921     9004   +83     
=======================================
+ Hits         8921     9004   +83     

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[Copilot]

Pull request overview

Adds serde-compatible configuration structs and .config() convenience methods to seatbelt middleware so users can load resilience settings from external config files (resolves #301).

Changes:

• Introduce RetryConfig, BreakerConfig, and TimeoutConfig (serde-gated) and expose them from their modules.
• Add .config(&...Config) methods on RetryLayer, BreakerLayer, and TimeoutLayer to apply config in one call; refactor enable/disable handling via a shared EnableIf enum.
• Add a config example (JSON + Rust) and snapshot tests verifying defaults and config application.

Reviewed changes

Copilot reviewed 32 out of 33 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/seatbelt/src/utils/mod.rs	Replace macro-based EnableIf with an enum supporting enabled/disabled/custom predicate.
crates/seatbelt/src/timeout/mod.rs	Add config module and re-export TimeoutConfig.
crates/seatbelt/src/timeout/layer.rs	Add TimeoutLayer::config and update enable/disable plumbing + snapshots in tests.
crates/seatbelt/src/timeout/config.rs	New serde-gated TimeoutConfig with duration-friendly serde formatting.
crates/seatbelt/src/timeout/snapshots/*	New snapshots for timeout defaults and config application.
crates/seatbelt/src/retry/mod.rs	Add config module and re-export RetryConfig.
crates/seatbelt/src/retry/layer.rs	Add RetryLayer::config applying all config fields.
crates/seatbelt/src/retry/config.rs	New serde-gated RetryConfig with duration-friendly serde formatting.
crates/seatbelt/src/retry/backoff.rs	Add serde derives for Backoff (feature-gated).
crates/seatbelt/src/retry/service.rs	Switch default assertions to snapshots.
crates/seatbelt/src/retry/snapshots/*	New snapshots for retry defaults and config application.
crates/seatbelt/src/breaker/mod.rs	Add config module and re-export BreakerConfig.
crates/seatbelt/src/breaker/layer.rs	Add BreakerLayer::config applying all config fields.
crates/seatbelt/src/breaker/service.rs	Switch default assertions to snapshots.
crates/seatbelt/src/breaker/config.rs	New serde-gated BreakerConfig with duration-friendly serde formatting.
crates/seatbelt/src/breaker/half_open_mode.rs	Add serde representation for HalfOpenMode + serde roundtrip tests.
crates/seatbelt/src/breaker/snapshots/*	New snapshots for breaker defaults and config application.
crates/seatbelt/src/fallback/layer.rs	Update enable/disable plumbing to new EnableIf.
crates/seatbelt/src/lib.rs	Document new serde feature.
crates/seatbelt/examples/config.rs	New example showing deserialization + .config() usage.
crates/seatbelt/examples/config.json	Example JSON config file.
crates/seatbelt/README.md	Document new serde feature.
crates/seatbelt/Cargo.toml	Add serde feature, deps (serde, jiff), dev deps (insta, serde_json), and example wiring.
Cargo.lock	Lockfile updates for new dependencies.

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