chore(settings): bump balanced/sonnet model to claude-sonnet-5

pi-fork balanced tier + enabledModels and the README examples now point at
eu.anthropic.claude-sonnet-5 (matches the live settings.json change made
before the container recreate).

settings.example.json

@@ -5,7 +5,7 @@
   "defaultProvider": "amazon-bedrock",
   "defaultModel": "eu.anthropic.claude-opus-4-8",
   "enabledModels": [
-    "eu.anthropic.claude-sonnet-4-6",
+    "eu.anthropic.claude-sonnet-5",
     "eu.anthropic.claude-opus-4-7",
     "eu.anthropic.claude-opus-4-8",
     "eu.anthropic.claude-haiku-4-5-20251001-v1:0"
@@ -23,7 +23,7 @@
     "defaultEffort": "balanced",
     "effortProfiles": {
       "fast":     { "provider": "amazon-bedrock", "id": "eu.anthropic.claude-haiku-4-5-20251001-v1:0", "thinking": "off" },
-      "balanced": { "provider": "amazon-bedrock", "id": "eu.anthropic.claude-sonnet-4-6",              "thinking": "low" },
+      "balanced": { "provider": "amazon-bedrock", "id": "eu.anthropic.claude-sonnet-5",                "thinking": "low" },
       "deep":     { "provider": "amazon-bedrock", "id": "eu.anthropic.claude-opus-4-8",               "thinking": "high" }
     }
   }