fix: scope the rescue to the guarded call in run strategies - #836

Fixes #766.

Problem

GreenRunStrategy#execute and YellowRunStrategy#execute wrapped the strategy's own post-success bookkeeping inside the same begin/rescue region as the user's guarded code.call. When a bookkeeping call raised on the success path, the exception was indistinguishable from a failure of the caller's code:

• it was passed to error_tracking_policy.track?,
• recorded via record_error / record_recovery_probe_failure, corrupting the success/failure metrics that drive tripping and recovery, and
• when a fallback was configured, the fallback was invoked with this synthetic error while the real, successful result was silently discarded.

Concretely:

• Green — the implicit begin covered code.call and the following record_success.
• Yellow — the recovery block covered enter_recovery (before the call) and record_recovery_probe_success (after it), not just code.call.

Fix

Scope the rescue to code.call only and run the success bookkeeping in an else clause; for yellow, run enter_recovery ahead of the guarded region as well. A bookkeeping/recovery failure on a successful call now surfaces as itself instead of being reclassified as a tracked run failure. The recovery lock is still released by the existing ensure in with_recovery_lock. No method signatures or RBS changed.

Tests

Added unit regressions that make a bookkeeping collaborator raise on the success path (as suggested in the issue):

• green — a raising record_success must surface the error, and must not consult track?, call record_failure, or invoke the fallback.
• yellow — the same for a raising record_recovery_probe_success and for a raising enter_recovery; both also assert the recovery lock is still released.

Each fails on the current code (the strategy swallows the error and returns the fallback value) and passes with the fix. The domain strategy files stay at 100% line coverage.

Validated with bundle exec rspec (712 examples, 0 failures), STOPLIGHT_DATA_STORE=Memory and STOPLIGHT_DATA_STORE=Redis bundle exec cucumber (62 scenarios each), bundle exec standardrb, and bundle exec steep check — all green.