Mortgage Calculator v2: stable results card, granular dashing, deferred errors, tax/insurance input fixes

[jenbreese]

READY FOR REVIEW

• Results card is now always visible with its full structure. Removed the all-or-nothing swap to an empty/coral panel that caused the card to disappear and reappear while editing.
• Per-line dashing by dependency: a result line shows "-" only when an input it depends on is empty/out-of-range; unaffected lines hold steady. Total dashes iff any component line (mortgage + tax + insurance + HOA) dashes.
• Range/limit errors now render as a banner above the card instead of replacing it.
• Fixed a render-loop "flicker" when a large tax/insurance dollar amount exceeded the 10%-of-price cap: the home price no longer collapses to 0 on a tax/insurance block (price depends only on payment/rate/term/down-payment), so the cap check is stable.
• Field errors now wait until the user leaves the field (focusedField suppression) for the required fields (monthly payment, home price, interest rate), instead of firing mid-edit while backspacing.
• Property tax & homeowners insurance inputs are now string-backed (both % and $, both tabs), matching the down-payment pattern: typing 0 shows 0 and the field can be cleared. Financial math is unchanged.
• Fixed color to the right teal.
• Fixed the results panel that had a light green background.
• Calcula

NOT READY FOR REVIEW

• (Edit the above to reflect status)

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