Bug: Drying.solve_unit initialization can omit temp_cond

[bernalde]

Parent: #118

Problem

One initialization branch in Drying.solve_unit packs satur, y_gas, x_liq, and temp_gas but omits temp_cond. The resulting vector is one block shorter than Drying.unit_model expects.

Acceptance criteria

• Add a focused regression test that exercises the affected initialization branch.
• Make every drying initialization branch conform to the same declared state layout.
• Validate the state-vector shape at the solver boundary.
• Keep this bug fix isolated from the wider StateLayout refactor.