Use strict comparisons throughout _checkNonce() validation

[flightlesstux]

Problem

GpgAuthenticator::_checkNonce() validates the GPG nonce format using loose != comparisons at every check. All values come from explode('|', $nonce) and are therefore strings, so loose coercion happens to produce correct results today — but PHP's type juggling rules make this fragile.

The UUID check is additionally wrong at the operand level:

// Comparing $version (the protocol string) against a bool return value
if ($version != Validation::uuid($uuid)) {

Validation::uuid() returns true/false. The comparison works only because 'gpgauthv1.3.0' == true and 'gpgauthv1.3.0' != false happen to be correct under loose coercion. This is an accident of PHP semantics, not intentional logic.

Fix

Replace every loose != with strict !==, and fix the UUID check to test the validation result directly:

if (count($result) !== 4) { ... }
if ($version !== $version2) { ... }
if ($version !== 'gpgauthv1.3.0') { ... }
if (!Validation::uuid($uuid)) { ... }       // was: $version != Validation::uuid($uuid)
if ($length !== '36') { ... }               // '36' string, since explode() returns strings

Notes

• $length is a string from explode(), so the strict comparison target changes from integer 36 to string '36'. The validation behaviour is identical.
• The UUID check is the most important fix: it removes a logically incorrect comparison that relied on double type coercion to pass.
• No functional change under any PHP version currently in use.

[CLAassistant]

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