chore(frontend): upgrade marked to v18

Bumps marked from 17.0.6 to 18.0.3. Used only in
src/lib/report/report-pdf.tsx for PDF generation via marked.lexer();
that API is compatible across the major.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/package.json

@@ -69,7 +69,7 @@
         "lowlight": "^3.3.0",
         "lru-cache": "^11.1.0",
         "lucide-react": "^1.16.0",
-        "marked": "^17.0.3",
+        "marked": "^18.0.3",
         "monaco-editor": "^0.55.1",
         "react": "^19.2.6",
         "react-day-picker": "^9.13.2",

frontend/pnpm-lock.yaml

@@ -162,8 +162,8 @@ importers:
         specifier: ^1.16.0
         version: 1.16.0(react@19.2.6)
       marked:
-        specifier: ^17.0.3
-        version: 17.0.6
+        specifier: ^18.0.3
+        version: 18.0.3
       monaco-editor:
         specifier: ^0.55.1
         version: 0.55.1
@@ -4644,8 +4644,8 @@ packages:
     engines: {node: '>= 18'}
     hasBin: true
 
-  marked@17.0.6:
-    resolution: {integrity: sha512-gB0gkNafnonOw0obSTEGZTT86IuhILt2Wfx0mWH/1Au83kybTayroZ/V6nS25mN7u8ASy+5fMhgB3XPNrOZdmA==}
+  marked@18.0.3:
+    resolution: {integrity: sha512-7VT90JOkDeaRWpfjOReRGPEKn0ecdARBkDGL+tT1wZY0efPPqkUxLUSmzy/C7TIylQYJC9STISEsCHrqb/7VIA==}
     engines: {node: '>= 20'}
     hasBin: true
 
@@ -10796,7 +10796,7 @@ snapshots:
 
   marked@14.0.0: {}
 
-  marked@17.0.6: {}
+  marked@18.0.3: {}
 
   math-intrinsics@1.1.0: {}