Calculation codes auto-complete from quantity

Line items now show calculation codes instead of dashes when the AI omits the formula.

What's Improved

When AI omits a calculation code formula but provides the correct quantity, we now infer which surface code (F, W, WC, PF, V) applies by matching the quantity against room dimensions. Line items no longer show dashes — every item displays its calculation code.

We also removed the redundant "Approved by client" chip from the estimate status bar. The revision dropdown already conveys approval status, so the chip just consumed header space.