fix(graphql): restore directChangedFiles field on Comparison type

[sentry]

This PR addresses issue API-EVX, where an external client was encountering a GraphQLError: Cannot query field 'directChangedFiles' on type 'Comparison'.

The root cause was that the Comparison GraphQL type only exposed directChangedFilesCount (an integer) but not the directChangedFiles connection field that the client was attempting to query.

To resolve this, the following changes were made:

1. Schema Update (apps/codecov-api/graphql_api/types/comparison/comparison.graphql):

   • Added the directChangedFiles(filters: ImpactedFilesFilters): ImpactedFilesResult! field to the Comparison type.

2. Resolver Implementation (apps/codecov-api/graphql_api/types/comparison/comparison.py):

   • A new resolver resolve_direct_changed_files was added.
   • This resolver utilizes the existing command.fetch_impacted_files method.
   • It explicitly sets has_unintended_changes=False in the filters to ensure that only files with direct changes are returned, aligning with the semantic meaning of 'direct changed files'.
   • The results are returned in the ImpactedFilesResult format, which is consistent with other file list queries.

Note for clients: While the field is restored, clients previously querying with Relay-style edges { node { headName } } will need to adjust their queries to use the results: [...] structure provided by ImpactedFilesResult.

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Fixes API-EVX

[thomasrockhu-codecov]

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Codecov Report

❌ Patch coverage is 37.50000% with 5 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...cov-api/graphql_api/types/comparison/comparison.py	37.50%	5 Missing ⚠️

❌ Your patch check has failed because the patch coverage (37.50%) is below the target coverage (90.00%). You can increase the patch coverage or adjust the target coverage.

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[codecov]

Codecov Report

❌ Patch coverage is 37.50000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.60%. Comparing base (68c86d1) to head (1b37e70).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...cov-api/graphql_api/types/comparison/comparison.py	37.50%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1981      +/-   ##
==========================================
- Coverage   91.61%   91.60%   -0.01%     
==========================================
  Files        1336     1336              
  Lines       53174    53182       +8     
  Branches     1647     1647              
==========================================
+ Hits        48715    48718       +3     
- Misses       4138     4143       +5     
  Partials      321      321              

Flag	Coverage Δ
apiunit	93.92% <37.50%> (-0.03%)	⬇️

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