Add persistent invoice template management

frontend/src/styles/global.css

@@ -751,6 +751,9 @@ a {
   grid-template-rows: auto minmax(0, 1fr);
   height: 100%;
   padding: 20px;
+  background: var(--surface-strong);
+  box-shadow: none;
+  backdrop-filter: none;
   overflow: hidden;
 }
 
@@ -854,13 +857,14 @@ a {
 }
 
 .invoice-template__canvas-shell {
+  position: relative;
   display: flex;
   justify-content: center;
   align-items: flex-start;
   height: 100%;
   min-height: 0;
   overflow: hidden;
-  padding: 0 0 8px;
+  padding: 0 0 10px;
   box-sizing: border-box;
 }
 
@@ -883,7 +887,6 @@ a {
     linear-gradient(90deg, transparent 31px, rgba(37, 49, 58, 0.05) 32px),
     #fffdf9;
   background-size: auto, 32px 32px, 32px 32px, auto;
-  box-shadow: 0 32px 60px rgba(54, 44, 27, 0.12);
   overflow: hidden;
   transform-origin: top left;
   will-change: transform;
@@ -891,7 +894,7 @@ a {
 
 .invoice-template__canvas.is-active {
   border-color: rgba(17, 109, 99, 0.48);
-  box-shadow: 0 32px 60px rgba(54, 44, 27, 0.12), 0 0 0 6px rgba(17, 109, 99, 0.08);
+  box-shadow: 0 0 0 6px rgba(17, 109, 99, 0.08);
 }
 
 .invoice-template__canvas::before {
@@ -924,9 +927,15 @@ a {
   color: var(--text);
   cursor: move;
   box-shadow: none;
+  overflow: visible;
   user-select: none;
 }
 
+.invoice-template__canvas-element--line,
+.invoice-template__canvas-element--image {
+  padding: 0;
+}
+
 .invoice-template__canvas-element:hover,
 .invoice-template__canvas-element.is-selected {
   border-color: rgba(17, 109, 99, 0.28);
@@ -938,6 +947,11 @@ a {
   z-index: 2;
 }
 
+.invoice-template__canvas-element.is-resizing {
+  cursor: nwse-resize;
+  z-index: 3;
+}
+
 .invoice-template__canvas-element-text {
   display: block;
   line-height: 1.35;
@@ -945,6 +959,56 @@ a {
   word-break: break-word;
 }
 
+.invoice-template__canvas-line {
+  display: block;
+  width: 100%;
+  height: 100%;
+  border-radius: 999px;
+  background: rgba(37, 49, 58, 0.82);
+  pointer-events: none;
+}
+
+.invoice-template__canvas-image {
+  display: block;
+  width: 100%;
+  height: 100%;
+  border-radius: 16px;
+  object-fit: contain;
+  pointer-events: none;
+}
+
+.invoice-template__canvas-image-placeholder {
+  display: grid;
+  place-items: center;
+  width: 100%;
+  height: 100%;
+  min-height: 100%;
+  padding: 12px;
+  border: 1px dashed rgba(17, 109, 99, 0.28);
+  border-radius: 18px;
+  background: rgba(17, 109, 99, 0.05);
+  color: var(--muted);
+  font-size: 0.82rem;
+  line-height: 1.4;
+  pointer-events: none;
+  text-align: center;
+}
+
+.invoice-template__canvas-element-resize-handle {
+  position: absolute;
+  right: -7px;
+  bottom: -7px;
+  width: 14px;
+  height: 14px;
+  border: 1px solid rgba(17, 109, 99, 0.48);
+  border-radius: 999px;
+  background: var(--surface-strong);
+  box-shadow: 0 0 0 3px rgba(17, 109, 99, 0.12);
+  cursor: nwse-resize;
+  pointer-events: auto;
+  touch-action: none;
+}
+
 .invoice-template__inspector {
   display: grid;
   gap: 12px;
@@ -957,7 +1021,9 @@ a {
 
 .invoice-template__inspector-actions {
   display: flex;
+  gap: 12px;
   justify-content: flex-end;
+  flex-wrap: wrap;
 }
 
 .invoice-template-page .field-grid {