fix(llm-parse): tolerate non-strict JSON from Gemini and similar models

Gemini reached through the OpenAI-compatible endpoint returns
JavaScript-object-literal output — single-quoted strings, unquoted keys,
trailing commas — which strict JSON.parse rejects. The reservation list
then came back empty and the booking-import UI showed nothing (#1638).

Add a shared parseLenientJson() that tries strict JSON first and falls
back to JSON5 (which accepts exactly that relaxed superset), and route
both the OpenAI-compatible and Ollama-native parse paths through it,
replacing the two identical strict parsers.

server/package.json

@@ -40,6 +40,7 @@
     "fast-xml-parser": "^5.5.10",
     "helmet": "^8.1.0",
     "jimp": "^1.6.1",
+    "json5": "^2.2.3",
     "jsonwebtoken": "^9.0.2",
     "node-cron": "^4.2.1",
     "nodemailer": "^9.0.1",