fix(worker): prevent OperationalError from expired ORM objects in UploadFinisher

[sentry]

This PR addresses an OperationalError: (psycopg2.OperationalError) server closed the connection unexpectedly occurring in app.tasks.upload.UploadFinisher.

Root Cause:
The _handle_finisher_lock method in UploadFinisher performs significant work, including finish_reports_processing. After this, it calls db_session.commit() (line 597) to update the repository's updatestamp. Due to SQLAlchemy's default expire_on_commit=True behavior, all ORM objects in the session, including the commit object, are expired at this point.

Immediately after the commit, invalidate_caches is called (line 609). Inside invalidate_caches, accessing attributes like commit.repoid triggers a lazy-load from the database. If the PostgreSQL connection has been closed by the server (e.g., due to an idle timeout during the preceding long-running tasks), this lazy-load attempt results in the OperationalError.

Solution:
To prevent accessing expired ORM objects on a potentially closed database connection, the necessary commit and repository attributes (such as repoid, branch, commitid, repository.service, repository.author.username, repository.name, repository.branch) are now eagerly read and stored into local variables before db_session.commit() is called. The invalidate_caches method has been refactored to accept these primitive values directly, eliminating any post-commit ORM attribute access that could trigger a lazy-load.

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Fixes WORKER-Z5D

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.83%. Comparing base (d8942db) to head (7e5da00).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1866   +/-   ##
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  Coverage   91.83%   91.83%           
=======================================
  Files        1332     1332           
  Lines       51830    51836    +6     
  Branches     1647     1647           
=======================================
+ Hits        47598    47604    +6     
  Misses       3911     3911           
  Partials      321      321           

Flag	Coverage Δ
workerintegration	58.53% <100.00%> (+0.01%)	⬆️
workerunit	90.40% <100.00%> (+<0.01%)	⬆️

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