chore(deps-dev): bump mermaid from 11.12.2 to 11.15.0

Bumps [mermaid](https://github.com/mermaid-js/mermaid) from 11.12.2 to 11.15.0.
- [Release notes](https://github.com/mermaid-js/mermaid/releases)
- [Commits](https://github.com/mermaid-js/mermaid/compare/mermaid@11.12.2...mermaid@11.15.0)

---
updated-dependencies:
- dependency-name: mermaid
  dependency-version: 11.15.0
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package.json

@@ -21,7 +21,7 @@
   "devDependencies": {
     "@types/node": "^25.9.0",
     "@voidzero-dev/vitepress-theme": "^4.8.4",
-    "mermaid": "^11.12.2",
+    "mermaid": "^11.15.0",
     "prettier": "^3.8.1",
     "typescript": "^6.0.3",
     "vitepress": "2.0.0-alpha.16",