fix(docs): restore pinned deps and pnpm 10 lockfile format

Renovate rewrote docs/pnpm-lock.yaml with its bundled pnpm, downgrading
the patchedDependencies block to the pre-10.34 scalar format, which fails
the CI frozen install with ERR_PNPM_LOCKFILE_CONFIG_MISMATCH, and also
bumped fumadocs/lucide-react past the versions pinned after the
2026-10-14 regression. Restore both files to the last known good state
(verified: pnpm 10.34.7 frozen install + full docs build pass) and stop
renovate from managing docs npm deps until its pnpm writes the 10.x
lockfile format.

docs/package.json

@@ -21,11 +21,11 @@
     "@types/mdx": "^2.0.13",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
-    "fumadocs-core": "16.17.4",
+    "fumadocs-core": "16.8.7",
     "fumadocs-mdx": "^14.3.2",
-    "fumadocs-ui": "16.17.4",
+    "fumadocs-ui": "16.8.7",
     "fzstd": "^0.1.1",
-    "lucide-react": "0.577.0",
+    "lucide-react": "0.515.0",
     "marked": "18.1.1",
     "next": "^16.3.0",
     "postcss": "^8.5.26",