fixes #25617; handle backend type aliasing in procParamTypeRel

[ringabout]

fixes #25617

This pull request introduces a stricter check for parameter type relations in the procParamTypeRel procedure. Specifically, it ensures that two types are not only structurally equal but also have the same backend type, taking type aliases into account.

Type relation checks:

• compiler/sigmatch.nim: In procParamTypeRel, added a check to ensure that if two types are considered equal (isEqual), they must also have the same backend type (using sameBackendTypePickyAliases). If not, the result is set to isNone, preventing false positives when type aliases differ.

[Copilot]

Pull request overview

This PR fixes #25617 by tightening proc-parameter type relation checks so that “semantically equal” parameter types must also agree at the backend/ABI level (including alias distinctions), preventing Nim from accepting assignments that later fail during C compilation.

Changes:

• Add an additional backend-type compatibility check in procParamTypeRel when the semantic relation is isEqual.
• Treat tyInferred similarly to tyAlias during structural equality setup to avoid false mismatches.
• Add a regression test covering uint vs csize_t proc assignment failures and extend concept coverage for cint.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
compiler/sigmatch.nim	Rejects proc-param matches that are semantically equal but backend-incompatible (alias-aware).
compiler/types.nim	Adjusts type equality preprocessing to skip tyInferred alongside tyAlias.
tests/proc/tbackendtypealias.nim	New regression test ensuring uint vs csize_t proc assignment is rejected at Nim level.
tests/concepts/tconcepts_issues.nim	Adds concept-related coverage to ensure common cint matching continues to work.

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