feat: add canvas tool panels (multi-grid, upscale, inpaint) and conditional grid mode

Add modal-based tool panels for multi-grid, super-resolution, and inpaint in canvas image-to-image workflow. Grid mode selector only appears for models that support multi-image generation (wan2.7-image, gpt-image-2). Also fixes merge conflict markers in CSS and adds missing toast import.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/styles/pages/canvas.css

@@ -722,3 +722,191 @@
   right: -9999px;
   height: 1px;
 }
+
+/* Tool Modal Overlay */
+.studio-canvas-tool-modal-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 9000;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: rgba(0, 0, 0, 0.55);
+  backdrop-filter: blur(4px);
+}
+
+.studio-canvas-tool-modal {
+  position: relative;
+  width: 90vw;
+  max-width: 720px;
+  max-height: 80vh;
+  overflow-y: auto;
+  border-radius: 16px;
+  background: var(--bg-panel);
+  border: 1px solid var(--border-subtle);
+  box-shadow: var(--shadow-heavy, 0 12px 40px rgba(0,0,0,0.4));
+  padding: 24px;
+}
+
+.studio-canvas-tool-modal__header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-bottom: 16px;
+}
+
+.studio-canvas-tool-modal__title {
+  font-size: 16px;
+  font-weight: 600;
+  color: var(--fg-default);
+}
+
+.studio-canvas-tool-modal__close {
+  width: 32px;
+  height: 32px;
+  border-radius: 8px;
+  border: none;
+  background: var(--bg-subtle);
+  color: var(--fg-muted);
+  cursor: pointer;
+  font-size: 18px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  transition: background 0.15s;
+}
+
+.studio-canvas-tool-modal__close:hover {
+  background: var(--bg-hover);
+}
+
+/* Tool Panel Components */
+.studio-canvas-tool-panel {
+  display: flex;
+  gap: 20px;
+  min-height: 280px;
+}
+
+.studio-canvas-tool-panel--inpaint {
+  flex-direction: column;
+}
+
+.studio-canvas-tool-panel__preview {
+  flex: 0 0 260px;
+  border-radius: 10px;
+  overflow: hidden;
+  background: var(--bg-subtle);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.studio-canvas-tool-panel__preview img {
+  width: 100%;
+  height: 100%;
+  object-fit: contain;
+}
+
+.studio-canvas-tool-panel__controls {
+  flex: 1;
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
+}
+
+.studio-canvas-tool-panel__label {
+  font-size: 13px;
+  font-weight: 500;
+  color: var(--fg-muted);
+}
+
+.studio-canvas-tool-panel__options {
+  display: flex;
+  gap: 8px;
+}
+
+.studio-canvas-tool-panel__options button {
+  padding: 6px 16px;
+  border-radius: 8px;
+  border: 1px solid var(--border-subtle);
+  background: var(--bg-subtle);
+  color: var(--fg-default);
+  cursor: pointer;
+  font-size: 13px;
+  transition: all 0.15s;
+}
+
+.studio-canvas-tool-panel__options button.is-active {
+  background: var(--accent);
+  border-color: var(--accent);
+  color: #fff;
+}
+
+.studio-canvas-tool-panel__textarea {
+  width: 100%;
+  min-height: 60px;
+  padding: 10px;
+  border-radius: 8px;
+  border: 1px solid var(--border-subtle);
+  background: var(--bg-subtle);
+  color: var(--fg-default);
+  font-size: 13px;
+  resize: vertical;
+}
+
+.studio-canvas-tool-panel__submit {
+  margin-top: auto;
+  padding: 10px 20px;
+  border-radius: 8px;
+  border: none;
+  background: var(--accent);
+  color: #fff;
+  font-size: 14px;
+  font-weight: 500;
+  cursor: pointer;
+  transition: opacity 0.15s;
+}
+
+.studio-canvas-tool-panel__submit:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.studio-canvas-tool-panel__actions {
+  display: flex;
+  gap: 10px;
+  margin-top: auto;
+}
+
+.studio-canvas-tool-panel__reset {
+  padding: 10px 16px;
+  border-radius: 8px;
+  border: 1px solid var(--border-subtle);
+  background: var(--bg-subtle);
+  color: var(--fg-default);
+  font-size: 13px;
+  cursor: pointer;
+}
+
+.studio-canvas-tool-panel__canvas-wrap {
+  position: relative;
+  width: 100%;
+  max-height: 320px;
+  border-radius: 10px;
+  overflow: hidden;
+  background: var(--bg-subtle);
+}
+
+.studio-canvas-tool-panel__canvas-bg {
+  width: 100%;
+  height: auto;
+  display: block;
+}
+
+.studio-canvas-tool-panel__canvas {
+  position: absolute;
+  inset: 0;
+  width: 100%;
+  height: 100%;
+  cursor: crosshair;
+}

src/styles/pages/script-tokens-v5.css

@@ -3577,8 +3577,6 @@
     font-size: 13px;
   }
 }
-<<<<<<< HEAD
-=======
 
 /* Script review left panel overflow guard: keep actions available while history remains scrollable. */
 .script-eval-v5-left {
@@ -4087,4 +4085,3 @@
 .script-eval-v5.is-ready .script-eval-v5-status-dot {
   box-shadow: none;
 }
->>>>>>> c1c4086383ddd7c1c8c152c2d5a97a4f432fa260