Fix variable shadowing and linting violations in security fix

[Copilot]

The security fix for path traversal (PR #[number]) introduced variable shadowing and testifylint violations that prevented linting from passing.

Changes

Fixed variable shadowing in completions.go:

• Renamed parameter filepath → filePath to avoid shadowing the path/filepath package
• Security fix logic unchanged (path sanitization and absolute path validation intact)

// Before: shadowed package name
func getWorkflowDescription(filepath string) string {
    cleanPath := filepath.Clean(filepath)  // ❌ ambiguous
    ...
}

// After: clear reference
func getWorkflowDescription(filePath string) string {
    cleanPath := filepath.Clean(filePath)  // ✅ unambiguous
    ...
}

Fixed testifylint violations in interfaces_test.go:

• Changed assert.NoError → require.NoError for error assertions per testing guidelines
• Critical setup failures now halt test execution immediately

Automatic cleanup:

• Removed unused context imports via golangci-lint

All linting checks now pass.

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