fix-9341-parse-dotted-osi-underlying

[aiSynergy37]

Description

Fixes OSI option ticker parsing when the underlying contains a dot such as BRK.B.

Changes:

• Allow . and / in the underlying segment of the OSI regex.
• Add regression coverage for BRK.B 260206C00495000.

Closes #9341.

Validation

• dotnet build Tests/QuantConnect.Tests.csproj --configuration Release /p:RunAnalyzers=false
• dotnet test Tests/QuantConnect.Tests.csproj --configuration Release --filter FullyQualifiedName~QuantConnect.Tests.Common.SymbolRepresentationTests.ParseOptionTickerOSI --no-build (fails in this local environment due pythonnet GIL teardown and missing local Data map files)

[AlexCatarino]

Duplicate: #9343