Add grid cell inventory linking and component quick-create

- New 'grid' location type on inventory entries (grid_id, grid_row, grid_col)
- Clicking a grid cell shows a popup with what's stored there
- Popup has '+ Add entry' pre-filled with the cell coordinates
- Inventory dialog: 'New...' button next to component selector opens
  component creation dialog on top, returns with new component selected
- Grid entries display as e.g. 'Black Component Box R3C5' in lists
- Store original filename on source image upload

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/style.css

@@ -1019,6 +1019,17 @@ nav {
 
 /* ===== FORM ROW PAIR ===== */
 
+.input-with-action {
+	display: flex;
+	gap: 0.4rem;
+	align-items: center;
+}
+
+.input-with-action .filter-select {
+	flex: 1;
+	min-width: 0;
+}
+
 .form-row-pair {
 	display: grid;
 	grid-template-columns: 1fr 1fr;
@@ -1311,3 +1322,95 @@ nav {
 	text-align: center;
 	font-family: var(--font-mono);
 }
+
+/* ===== GRID TYPE PILL ===== */
+
+.type-pill.type-grid {
+	background: #2e7d4f;
+	color: #fff;
+}
+
+/* ===== GRID CELL PICKER (inventory dialog) ===== */
+
+.i-grid-cell-picker {
+	display: flex;
+	flex-direction: column;
+	gap: 0.4rem;
+}
+
+.i-grid-coords {
+	display: flex;
+	align-items: center;
+	gap: 0.4rem;
+	font-size: 0.9rem;
+}
+
+.input-narrow {
+	width: 4rem;
+}
+
+/* ===== CELL INVENTORY OVERLAY ===== */
+
+.grid-cell {
+	cursor: pointer;
+}
+
+.cell-inventory-overlay {
+	position: fixed;
+	background: var(--surface);
+	border: 1px solid var(--border);
+	border-radius: 6px;
+	padding: 0.75rem;
+	min-width: 220px;
+	max-width: 320px;
+	box-shadow: 0 4px 16px rgba(0,0,0,0.4);
+	z-index: 100;
+}
+
+.cell-inventory-header {
+	display: flex;
+	justify-content: space-between;
+	align-items: center;
+	margin-bottom: 0.5rem;
+}
+
+.cell-inventory-title {
+	font-weight: 600;
+	font-size: 0.9rem;
+}
+
+.cell-inventory-list {
+	display: flex;
+	flex-direction: column;
+	gap: 0.25rem;
+	margin-bottom: 0.5rem;
+	min-height: 1rem;
+}
+
+.cell-inv-item {
+	font-size: 0.85rem;
+	display: flex;
+	justify-content: space-between;
+	gap: 0.5rem;
+}
+
+.cell-inv-qty {
+	color: var(--text-dim);
+	white-space: nowrap;
+}
+
+.cell-inv-empty {
+	font-size: 0.85rem;
+	color: var(--text-faint);
+	font-style: italic;
+}
+
+.cell-inventory-actions {
+	display: flex;
+	justify-content: flex-end;
+}
+
+.btn-sm {
+	padding: 0.25rem 0.6rem;
+	font-size: 0.82rem;
+}