fix: popups no longer close on backdrop click, only via explicit close/cancel

Clicking the dimmed area outside a modal (+Task, +Invoice, expense,
review, etc.) accidentally dismissed it and lost in-progress input.
Every popup already has an explicit Cancel/Close/✕ button, so the
backdrop click handler is removed; also drops the now-dead
onClose/blockClose prop plumbing that only existed to support it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/components/InvoiceDetailPopup.jsx

@@ -15,8 +15,6 @@ export default function InvoiceDetailPopup({
   title,
   subtitle,
   headerRight,
-  onClose,
-  blockClose = false,
   metaContent,   // JSX fields rendered in flat meta grid (no cards)
   metaActions,   // optional JSX rendered right-aligned beside meta grid (e.g. Edit Dates)
   metaCols = 4,  // number of grid columns for meta strip
@@ -25,7 +23,7 @@ export default function InvoiceDetailPopup({
   children,
 }) {
   return (
-    <div style={popupOverlayStyle} onClick={() => { if (!blockClose) onClose?.(); }}>
+    <div style={popupOverlayStyle}>
       <div
         style={{ ...popupSurfaceStyle, width: '80vw', height: '80vh', display: 'flex', flexDirection: 'column', gap: 0 }}
         onClick={e => e.stopPropagation()}