feat: add scope merging mechanism

[giortzisg]

Description

Issues

• resolves: Add scope merging for global and isolation scopes #1369
• resolves: GO-155

Changelog Entry Instructions

To add a custom changelog entry, uncomment the section above. Supports:

• Single entry: just write text
• Multiple entries: use bullet points
• Nested bullets: indent 4+ spaces

For more details: custom changelog entries

Reminders

• Add GH Issue ID & Linear ID
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[linear-code]

GO-155

[sentry]

Bug: The NewMeter and NewLogger functions no longer return no-op instances when the client is disabled, leading to unnecessary work.
_{Severity: MEDIUM}

Suggested Fix

Reinstate the client.IsEnabled() check in the conditional logic for NewMeter in metrics.go and NewLogger in log.go. This will ensure that a no-op instance is returned when the client is disabled, preserving the original behavior and matching the documentation.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: metrics.go#L58-L59

Potential issue: The `client.IsEnabled()` check was removed from the `NewMeter` and
`NewLogger` factory functions. As a result, if the Sentry SDK is not initialized (e.g.,
no DSN is configured), these functions will now return real `sentryMeter` and
`sentryLogger` instances instead of the intended no-op versions. This causes unnecessary
CPU and memory usage to build metrics and logs that are ultimately discarded, and it
creates a mismatch between the code's behavior and its documentation, which states that
a no-op instance should be returned when the client is disabled.

Also affects:

• log.go:63~64

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit f1ba13c. Configure here.}