[ViktorBystrov72]

FlagSet.Visit reuses its sorted cache after SetNormalizeFunc renames flags. If the new names sort differently, visits no longer follow the documented lexicographical order. For example, visiting middle,zulu, then aliasing zulu to alpha, produces middle,alpha instead of alpha,middle.

Invalidate the sorted set-flag cache alongside the existing declared-flag cache. The regression test populates the cache before normalization and checks both sorted visits and insertion-order visits, including an unset flag that must remain excluded.

Validation on macOS arm64 with Go 1.27.3:

• The sorted regression fails on unchanged master with [middle alpha], then passes with this change.
• go test -race -count=1 ./... passes.
• Repository-configured golangci-lint run ./... (2.14.0) reports no issues.
• gofmt and git diff --check pass.

The older Go versions in the CI matrix were not run locally; the change uses the module's existing Go 1.12-compatible syntax.

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