feat(mantine)!: upgrade to Mantine 9

Bumps @mantine/core and @mantine/code-highlight peers from ^8.3.17 to
^9.0.0 (dev-tested against 9.4.1) and declares @mantine/hooks
explicitly — core@9 pins its hooks peer exactly, and the previously
auto-installed 8.3.17 could no longer satisfy it.

Zero code changes required: the package's API surface (Typography,
MantineProvider, useComputedColorScheme, ActionIcon/CopyButton/Flex/
Tooltip, CodeHighlight adapter family) survives every 9.0 breaking
change — the source already used the Typography name, no removed props
or split hooks are referenced, and the SCSS only overrides CSS
variables v9 retains. Consumers inherit v9's visual defaults (radius
md, solid light-variant colors) and its React 19.2 floor.

Verified: SSR smoke suite, full preflight, and a live storybook pass
(CodeHighlightTabs with collapse/copy, JSON deep-parse, mermaid with
ActionIcons, KaTeX, tables — zero console errors).

BREAKING CHANGE: peer dependencies now require @mantine/core ^9.0.0
and @mantine/code-highlight ^9.0.0 (which require react >=19.2).

Author: AIEPhoenix

packages/mantine/package.json

@@ -57,8 +57,8 @@
   },
   "peerDependencies": {
     "@ai-react-markdown/core": "^1.4.9",
-    "@mantine/code-highlight": "^8.3.17",
-    "@mantine/core": "^8.3.17",
+    "@mantine/code-highlight": "^9.0.0",
+    "@mantine/core": "^9.0.0",
     "highlight.js": "^11.11.1",
     "react": ">=19",
     "react-dom": ">=19"
@@ -69,8 +69,9 @@
   },
   "devDependencies": {
     "@ai-react-markdown/core": "workspace:*",
-    "@mantine/code-highlight": "^8.3.18",
-    "@mantine/core": "^8.3.18",
+    "@mantine/code-highlight": "^9.4.1",
+    "@mantine/core": "^9.4.1",
+    "@mantine/hooks": "^9.4.1",
     "@types/lodash-es": "^4.17.12",
     "@types/node": "^25.9.5",
     "autoprefixer": "^10.5.2",