Scalibility improvementsd

[iazaran]

Pull Request

Description

After-commit deferral — model cache flushes now wait for DB commit, preventing stale re-caching mid-transaction.
Tag metadata hardening — locked read-modify-write for tag indexes and dependencies (fixing lost updates), namespace-aware tag flushing, and dead-reference pruning.
Dedup fix — identical re-writes no longer skip when the value was evicted but its hash survived.
Observability — new TagFlushed event exposing the flush source (manual/model/model_helper).
Backward compatibility — interface signature kept unchanged (optional $source only on the concrete class), and the declarative cacheInvalidation() method is guarded against signature collisions.

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce.

• Test Locally

Test Configuration:

• PHP version: 8.5
• Laravel version: 13

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules