Quantity calculations now display with formulas and tooltips

See exactly how line item quantities are calculated — formulas like W (walls) and PF×FH (flood-cut area) now display with plain-language explanations.

What's New

The estimate line items table now displays quantity calculations as formulas instead of just unit abbreviations. Each calculation shows a tooltip explaining the formula (e.g., "W = walls", "PF × FH = walls below flood line"), making it clear how quantities are being computed.

When creating or editing line items via voice input, the calculation field is now labeled "Calculation" (not "Quantity") and includes placeholders like W, WC, and PF * FH to guide users toward formula-based calculations.

Under the Hood

The AI estimate pipeline now preserves quantity formulas sourced from room scoping through to the final estimates, preventing loss of calculation context. Calculations are normalized and validated to ensure only meaningful dimensional formulas (not plain counts like "1" or "42") are stored.