Add settings page, model management, and chat UX improvements

- Settings infrastructure: key-value settings table, GET/PUT API, Pinia store
- Configurable assistant name (default "Fable") in settings and LLM system prompt
- Model catalog with 18 models in 3 categories (General Purpose, Coding,
  Uncensored / Creative Writing) with download/select/remove functionality
- Move Ollama status indicator from chat views to global nav bar
- Chat bubble layout: user messages right-aligned, assistant left-aligned
- Floating dark input bar with auto-focus and circular send button
- Fix HTML entity rendering (' apostrophe issue in marked/DOMPurify pipeline)
- Fix new chat button navigation (fetchConversation before router.push)
- Recent chats section on home page with "New Chat" button
- Update summary.md with Phase 4.5 changes

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

frontend/src/utils/markdown.ts

@@ -2,20 +2,31 @@ import { marked } from "marked";
 import DOMPurify from "dompurify";
 import { linkifyTags, linkifyWikilinks } from "@/utils/tags";
 
+function decodeEntities(text: string): string {
+  const textarea = document.createElement("textarea");
+  textarea.innerHTML = text;
+  return textarea.value;
+}
+
 export function renderMarkdown(text: string): string {
-  const html = marked(text) as string;
+  const decoded = decodeEntities(text);
+  const html = marked(decoded) as string;
   const withTags = linkifyTags(html);
   const withLinks = linkifyWikilinks(withTags);
-  return DOMPurify.sanitize(withLinks, {
+  const sanitized = DOMPurify.sanitize(withLinks, {
     ADD_ATTR: ["data-tag", "data-title"],
   });
+  // marked escapes ' to ' — replace after sanitization to ensure clean rendering
+  return sanitized.replace(/'/g, "'");
 }
 
 export function renderPreview(text: string): string {
-  const html = marked(text) as string;
+  const decoded = decodeEntities(text);
+  const html = marked(decoded) as string;
   const withTags = linkifyTags(html);
   const withLinks = linkifyWikilinks(withTags);
-  return DOMPurify.sanitize(withLinks, {
+  const sanitized = DOMPurify.sanitize(withLinks, {
     FORBID_TAGS: ["a", "img"],
   });
+  return sanitized.replace(/'/g, "'");
 }