Refactor toast notifications and modal dialog implementation

- Updated SCSS for toast notifications to support multiple toast types (success, info, warning, error) and improved layout.
- Added new SVG icons for error, info, success, and warning notifications.
- Created separate HTML templates for toast notifications and modal dialogs.
- Enhanced the dev panel with buttons to test different toast notifications and modal dialogs.

backend/static/warning.svg

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   width="40.905399mm"
+   height="40.905399mm"
+   viewBox="0 0 40.905399 40.905399"
+   version="1.1"
+   id="svg1"
+   sodipodi:docname="warning.svg"
+   inkscape:version="1.4 (86a8ad7, 2024-10-11)"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <sodipodi:namedview
+     id="namedview1"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:showpageshadow="2"
+     inkscape:pageopacity="0.0"
+     inkscape:pagecheckerboard="true"
+     inkscape:deskcolor="#d1d1d1"
+     inkscape:document-units="mm"
+     inkscape:zoom="1.0396254"
+     inkscape:cx="-80.79833"
+     inkscape:cy="65.889115"
+     inkscape:window-width="2560"
+     inkscape:window-height="1369"
+     inkscape:window-x="-8"
+     inkscape:window-y="828"
+     inkscape:window-maximized="1"
+     inkscape:current-layer="layer1" />
+  <defs
+     id="defs1" />
+  <g
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer"
+     id="layer1"
+     transform="translate(-80.178404,-120.49168)">
+    <path
+       style="fill:#ffff1a;fill-opacity:1;stroke:#616100;stroke-width:5.513;stroke-linecap:butt;stroke-linejoin:round;stroke-dasharray:none;stroke-opacity:1;paint-order:stroke fill markers"
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+       id="path1"
+       sodipodi:nodetypes="cccc" />
+    <path
+       style="font-size:37.4875px;font-family:'Arial Rounded MT Bold';-inkscape-font-specification:'Arial Rounded MT Bold, ';fill:#000000;fill-opacity:1;stroke-width:2.49752"
+       d="m 98.737968,144.66325 -0.550671,-8.24286 q -0.154876,-2.40918 -0.154876,-3.4589 0,-1.4283 0.739965,-2.2199 0.757173,-0.80879 1.978984,-0.80879 1.47992,0 1.97897,1.03251 0.49904,1.01529 0.49904,2.94265 0,1.13576 -0.12046,2.30593 l -0.73996,8.48378 q -0.12047,1.51435 -0.51626,2.32314 -0.39579,0.8088 -1.30784,0.8088 -0.929259,0 -1.290638,-0.77438 -0.361377,-0.79159 -0.516254,-2.39198 z m 1.910142,11.32318 q -1.049718,0 -1.841307,-0.67113 -0.774382,-0.68834 -0.774382,-1.91015 0,-1.06692 0.739965,-1.80688 0.757173,-0.75717 1.841304,-0.75717 1.08413,0 1.84131,0.75717 0.77438,0.73996 0.77438,1.80688 0,1.2046 -0.77438,1.89294 -0.77438,0.68834 -1.80689,0.68834 z"
+       id="text1"
+       aria-label="!" />
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+</svg>