PSNR format-table analyzer cleanup¶

The configured Cppcheck run flagged the private C++ FormatEntry::params member as lacking a default initializer and suggested a standard lookup algorithm. All twelve entries in the existing constexpr table already initialize both fields; no uninitialized runtime access was demonstrated.

Give the private member an empty default initializer and use std::ranges::find projected through FormatEntry::fmt. The first exact string match still supplies the same constants. The optional lookup result is read-only. Removing an unnecessary uncited cert-err58-cpp marker leaves the complete translation unit clean without a replacement suppression.

The configured CPU C++26 compiler builds both original and changed source. A differential probe verifies 68 cases: twelve supported formats, four unsupported strings and a null format, each with ordinary output pointers, a null peak, a null ceiling and aliased outputs. Return codes and output double bytes match. All twelve table initializer rows are textually unchanged. Actual clang-tidy and Cppcheck report no source diagnostics; the scoped baseline writer removes one uncited marker allowance and changes no other source allowance.

No new policy, alternatives or rebase-sensitive invariant is introduced. The existing C entry point and header remain unchanged; no FFmpeg patch or human usage change is needed. The probe, native compiler commands and raw analyzer receipts are retained under .workingdir2/evidence/psnr-format-table-lint-20260908/.