feat: allow trailing commas in config schema

Uses extension defined in [vscode-json-languageservice][vscode-json].
Also works with Zed and probably other editors too.

[vscode-json]: https://github.com/microsoft/vscode-json-languageservice/blob/5d87d160f018533c4eb3b996b54252f900a1e062/src/jsonSchema.ts#L89

Author: marmitar

dcp.schema.json

@@ -5,6 +5,7 @@
     "description": "Configuration schema for the OpenCode Dynamic Context Pruning plugin",
     "type": "object",
     "additionalProperties": false,
+    "allowTrailingCommas": true,
     "properties": {
         "$schema": {
             "type": "string",