fix: show literal ascii sequences instead of arrow ligatures (#29595)

Inter ships arrow substitutions as OpenType contextual alternates, and
Open WebUI sets no font-variant-ligatures, so a sequence like <--- is
stored and sent exactly as typed while being drawn as an arrow. Reported
as text conversion in #29594, where the memory rule had in fact worked
and only the display was misleading.

Reading the DOM back with the bundled Inter file loaded in isolation
confirms every field holds U+3C U+2D U+2D U+2D. Only the glyphs differ.

no-contextual rather than none: none, no-contextual, and
font-feature-settings "calt" 0 all fix it, which places the arrow in
contextual alternates. no-contextual disables that one feature and
leaves standard ligatures intact, so ordinary prose is unaffected.

Set on html, next to the existing document-wide typography, so it
inherits to editable fields and rendered content without a new selector.
Scoping it to inputs would fix the field you type into and leave the
memory list and chat messages still drawing arrows.

src/app.css

@@ -19,6 +19,7 @@
 
 html {
 	word-break: break-word;
+	font-variant-ligatures: no-contextual;
 	/* font-size scales the entire document via the same UI control */
 	font-size: calc(1rem * var(--app-text-scale, 1));
 }