Structural engineering calculations overhauled

Key improvements in this work:

• Snow, wind, roof live load, and seismic demands are now calculated from ASCE 7-22 load combinations.
• Member checks (posts, beams, purlins, girts) run against NDS design values and fail the package if a member does not pass — several real failures were caught and corrected during development.
• Foundation sizing is derived from actual structural reactions rather than a fixed convention.
• Lateral resistance now accounts for diaphragm action with the correct wind coefficients.
• A manufactured truss path is available: truss source, hash verification, and a deferred-submittal sheet for the truss RFQ.
• PE-directed overrides are tracked and invalidated if the underlying design changes.
• The calc package is rendered and exportable.