[cpp-qt-client] Remove deprecated SignalE/SignalEFull signals in API classes

[MartinDelille]

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@ravinikam (2017/07) @stkrwork (2017/07) @etherealjoy (2018/02) @MartinDelille (2018/03) @muttleyxd (2019/08) @aminya (2025/05)

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Summary by cubic

Removed deprecated SignalE and SignalEFull error signal declarations and emissions from the cpp-qt client. The generator and samples now use SignalError and SignalErrorFull only, simplifying the API.

• Refactors

  • Updated api-header.mustache and api-body.mustache to remove deprecated signals and their emissions.
  • Regenerated petstore cpp-qt and cpp-qt-addDownloadProgress sources/headers.

• Migration

  • Replace XxxSignalE(...) with XxxSignalError(...).
  • Replace XxxSignalEFull(...) with XxxSignalErrorFull(...).
  • Update slots/lambdas to accept const QString & error_str instead of QString.

^{Written for commit d6113cc. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 11 files

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