Fixed some bugs related to the TFM solver

[arfazeli]

Fixes several issues in the TFM solver:

• Removes the incorrect dt scaling from the mixture injection source.
• Applies injected momentum to the dispersed phase using the primitive-form source mdot / Ad_safe * (inj_vec - ud).
• Adds the missing interior-facet contribution -avg(q) * jump(Ac) * ((uc - ud) * n) required for conservative mixture continuity with discontinuous volume fractions.
• Rejects non-finite Picard solutions instead of reporting false convergence.
• Moves laminar dispersion into the bilinear form using the Picard linearization InnerProduct(wd - wc, ud - uc), reducing sensitivity to large explicit updates.