Third-review fix for a CI blocker: run-platform-coverage-gate.sh only
executes ^(TestAllShortcuts|TestCrossPlatformCoverage) yet enforces 100%
coverage of changed production lines, so the TestResolveInputFlags names
left every new input.go statement reported as uncovered. Rename them to
the gate prefix, drop three unreachable pflag Set error branches that no
test could ever cover, and add the reachable stdin read-failure case.
Verified: changed code coverage 100.0000% (67 statements).