T25a Generative: prompt and settings

PromptEnhancer offers a fuller prompt with the words it adds washed,
split at punctuation; Use this takes it into the field, Keep mine
lets it go. StylePresetPicker and AspectRatioPicker are rows of Tab
stops, the chosen one in accent; a ratio chip draws its shape.
SeedInput keeps digits up to u32::MAX and rolls one with a die.
NegativePromptInput and ImageGenerationPanel point to forms::TagInput
and forms::Form. theme.generative() holds the chapter's sizes. The
gallery's preset pictures are the atrium photo in five styles.

assets/icons/ban.svg

@@ -0,0 +1,16 @@
+<!-- @license lucide-static v1.48.0 - ISC -->
+<svg
+  class="lucide lucide-ban"
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <circle cx="12" cy="12" r="10" />
+  <path d="M4.929 4.929 19.07 19.071" />
+</svg>

assets/icons/dices.svg

@@ -0,0 +1,20 @@
+<!-- @license lucide-static v1.48.0 - ISC -->
+<svg
+  class="lucide lucide-dices"
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <rect width="12" height="12" x="2" y="10" rx="2" ry="2" />
+  <path d="m17.92 14 3.5-3.5a2.24 2.24 0 0 0 0-3l-5-4.92a2.24 2.24 0 0 0-3 0L10 6" />
+  <path d="M6 18h.01" />
+  <path d="M10 14h.01" />
+  <path d="M15 6h.01" />
+  <path d="M18 9h.01" />
+</svg>