fix(pluto): Handle write operations inside FlatMap with Future

[coveloper]

Description:

Identus example app consistently throws a recursive save error when calling .sendMessage() as described in #183

Wrapping these .flatMap write operations in a Future seems to fix it in my example.
*note: If this is an acceptable fix, we might need to add another similar Future inside addMessages()'s .flatMap

Alternatives Considered (optional):

I had tried adding guard self.hasChanges else { return } on line 12 of NSManagedObjectContext+Save.swift but that didn't seem to have any effect on this issue.

Checklist:

• My PR follows the contribution guidelines of this project
• My PR is free of third-party dependencies that don't comply with the Allowlist
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked the PR title to follow the conventional commit specification

[coveloper]

Looks like a test failed. Are these tests I can run locally as part of my future PRs? or do they only run on Actions?