Add centralized error reporting via Rage::Errors

[Digvijay-x1]

Allow users to register error reporters that receive all framework-caught exceptions, so they can forward them to services like Sentry or Bugsnag without manually rescuing in every component.

  Rage.configure do
    config.errors << SentryReporter.new
  end

Reporters can accept just the exception or an optional context hash. Signature detection uses Rage::Internal.build_arguments at registration time to keep the reporting path fast. Each reporter is called in its own rescue block so a broken reporter doesn't affect the rest. Duplicate prevention uses an instance variable on the exception (similar to Rails). Manually-created exceptions get a real backtrace via re-raise rather than set_backtrace(caller).
Hooked into all existing framework rescue sites: controllers, fiber wrapper, Cable connections/channels, Redis adapter, deferred tasks, event subscribers, SSE streams, and telemetry tracers.

Fixes #232

[rsamoilov]

Hey @Digvijay-x1 ,

I usually don't review in-progress PRs, so I haven't looked at this one yet. Anything I can help with? Do you want me to give it a look?

[Digvijay-x1]

Hey @Digvijay-x1 ,

I usually don't review in-progress PRs, so I haven't looked at this one yet. Anything I can help with? Do you want me to give it a look?

Hey @rsamoilov,

Thanks for offering to help :)

Before requesting a review, I wanted to test whether all cases behave as expected. This took a bit longer since I had some college assignments last week.

From my testing so far, the core error reporting API appears to be working well. I set up a small Rage app with Sentry integration and verified that reporter registration, error forwarding, context propagation, duplicate prevention, and backtrace generation all behave correctly.

I’ve tested 5 out of the 9 call sites so far — including unhandled controller exceptions (covering both application.rb and fiber_wrapper.rb), deferred task failures, and direct Rage::Errors.report calls.

The remaining areas (events/subscriber, SSE, Cable, Redis adapter, telemetry) all route through the same Rage::Errors.report method, which is already working as expected.

I think the PR is in a good state for review now. Would appreciate your feedback whenever you get a chance!