fix: gosec issue in epoch-naming

[alexandear]

This won't cause any issues because epoch-naming has not been released yet.

[Copilot]

Pull request overview

This PR addresses a gosec (Go security linter) issue in the epoch-naming rule by adding proper error handling for the TypeCheck() method call. The fix ensures that type-checking errors are properly captured and reported, following the established error handling pattern used in other rule implementations.

Key Changes

• Added error checking for file.Pkg.TypeCheck() with proper error reporting via lint.NewInternalFailure
• Cleaned up test data by removing an invalid blank identifier short declaration and adding proper unused variable handling
• Removed the gosec exclusion for epoch_naming.go from linting configuration

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
rule/epoch_naming.go	Added error handling for TypeCheck() call, returning internal failure with formatted error message
testdata/epoch_naming.go	Removed invalid short declaration syntax with blank identifier; added _ = c to prevent unused variable warning
.golangci.yml	Removed gosec exclusion for epoch_naming.go now that the security issue is fixed

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