master seal coverage: let_reassigned.t27 drifted after #8667 #8671

#8667 changed gen-zig for slice parameters, and auto-merged on its required checks while seal coverage was red for one spec: specs/tri/t27b/conformance/let_reassigned.t27 (gen-drift). It landed on master during the PR, after the moved-spec list had been computed.

The spec passes 9/9 before and after; only the dead var input = input_arg; shadow goes. Its seal needs the new gen hash.

Acceptance criteria

• tri seals drift reports 0 on master.
• Seal Coverage is green on master.

Boundary

.trinity/seals/conformance_T27bConformanceLetReassigned.json

User Scenarios

• Given the spec specs/tri/t27b/conformance/let_reassigned.t27 passes 9/9 tests before and after gen-zig: a pointer or slice parameter written through is not re-bound as var (Closes #8641) #8667
• When tri seals drift runs on master after gen-zig: a pointer or slice parameter written through is not re-bound as var (Closes #8641) #8667 merged with the changed gen-zig for slice parameters
• Then it reports 0 drift because the seal hash matches the new generated output (the dead var input = input_arg; shadow is gone)

Requirements

• FR-001: The seal file .trinity/seals/conformance_T27bConformanceLetReassigned.json MUST be updated to the new gen-zig hash for slice parameters
• FR-002: tri seals drift on master MUST report 0 drift for this spec
• FR-003: Seal Coverage CI MUST be green on master

Success Criteria

• tri seals drift exits 0 and reports 0 drift
• Seal Coverage check passes (green) on master
• .trinity/seals/conformance_T27bConformanceLetReassigned.json contains the updated hash