Complete durable workflow query contract coverage

[rmcdaniel]

Summary

• cover partial durable parameter metadata and malformed unnamed parameters through the public query validator
• raise the accepted coverage floor to the 85.51% result proven by main run 33520656271
• update the coverage contract branch identity from the retired v2 name to main

Verification

• 8 focused tests / 42 assertions pass with isolated Redis
• Easy Coding Standard passes
• PHPStan passes for the changed test
• coverage-ratchet self-test passes
• public-boundary scan passes

Contributes to #426.