Phase 4a: shadcn form primitives + case inline edit

Add dialog/select/textarea/label/progress/sonner components and wire
a Toaster into Providers. New zod schemas in lib/schemas/case.ts
mirror CaseCreateRequest/CaseUpdateRequest and feed react-hook-form
validation.

CaseEditDialog on the case detail Actions tab posts PUT /api/cases/{n}
with optimistic cache patching via useUpdateCase, showing toast
feedback on success/error.

shadcn's <Form> registry entry skipped at init (missing from the
nova preset); the dialog uses RHF directly against the same Input/
Textarea/Select primitives.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web-ui/package.json

@@ -17,12 +17,14 @@
     "clsx": "^2.1.1",
     "lucide-react": "^1.8.0",
     "next": "16.2.3",
+    "next-themes": "^0.4.6",
     "radix-ui": "^1.4.3",
     "react": "19.2.4",
     "react-dom": "19.2.4",
     "react-dropzone": "^15.0.0",
     "react-hook-form": "^7.72.1",
     "shadcn": "^4.2.0",
+    "sonner": "^2.0.7",
     "tailwind-merge": "^3.5.0",
     "tw-animate-css": "^1.4.0",
     "zod": "^4.3.6"