fix(markdown): load TikZ font stylesheet to keep text aligned

The obsidian-tikzjax bundle emits SVG referencing Computer Modern font
families like cmbx7 but ships the @font-face declarations in a separate
styles.css. Without it the browser substitutes a default font whose
glyph widths don't match TeX's, leaving visible gaps between each
kerned text run. Lazy-load the stylesheet alongside the engine on
first TikZ render so cache hits and misses both see correct fonts.

src/hooks/useMarkdown.hook.ts

@@ -28,6 +28,8 @@ import { markdownItTablerIcons } from "@/utils/markdown/markdown-it-tabler-icons
 
 const TIKZ_BUNDLE_URL =
   "https://cdn.jsdelivr.net/gh/artisticat1/obsidian-tikzjax@0.5.2/tikzjax.js"
+const TIKZ_STYLES_URL =
+  "https://cdn.jsdelivr.net/gh/artisticat1/obsidian-tikzjax@0.5.2/styles.css"
 const TIKZ_RENDER_TIMEOUT_MS = 30000
 
 const markdownItMermaidExtractor = (md: MarkdownIt) => {
@@ -188,6 +190,7 @@ export const runMermaid = (querySelector: string) => {
 }
 
 let tikzBundlePromise: Promise<void> | null = null
+let tikzStylesPromise: Promise<void> | null = null
 let domPurifyPromise: Promise<typeof import("dompurify")> | null = null
 
 const ensureTikzBundle = (): Promise<void> => {
@@ -215,6 +218,31 @@ const ensureTikzBundle = (): Promise<void> => {
   return tikzBundlePromise
 }
 
+const ensureTikzStyles = (): Promise<void> => {
+  if (tikzStylesPromise) return tikzStylesPromise
+
+  tikzStylesPromise = new Promise<void>((resolve, reject) => {
+    const existing = document.getElementById("tikzjax-styles")
+    if (existing) {
+      resolve()
+      return
+    }
+    const link = document.createElement("link")
+    link.id = "tikzjax-styles"
+    link.rel = "stylesheet"
+    link.href = TIKZ_STYLES_URL
+    link.crossOrigin = "anonymous"
+    link.addEventListener("load", () => resolve())
+    link.addEventListener("error", () => {
+      tikzStylesPromise = null
+      reject(new Error("Failed to load TikZ font styles"))
+    })
+    document.head.appendChild(link)
+  })
+
+  return tikzStylesPromise
+}
+
 const ensureDomPurify = (): Promise<typeof import("dompurify")> => {
   if (!domPurifyPromise) domPurifyPromise = import("dompurify")
   return domPurifyPromise
@@ -297,6 +325,8 @@ export const runTikz = async (querySelector: string): Promise<void> => {
   )
   if (elements.length === 0) return
 
+  void ensureTikzStyles().catch(() => undefined)
+
   await Promise.all(
     elements.map(async (el) => {
       if (el.dataset.tikzRendered) return