fix(admin): remove invalid 'multiline' property from excludePatterns

The JSON Config schema for type 'text' enforces additionalProperties:false
and 'multiline' is not a documented property. Its presence caused the
admin UI to fail schema validation and refuse to render the panel.

Multi-line behaviour is already provided by 'minRows: 6' alone — the
schema explicitly states: "Set this attribute to 2 or more if you want
to have a textarea with more than one row."

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

admin/jsonConfig.json

@@ -47,7 +47,6 @@
             "type": "text",
             "label": "Exclude patterns (one per line)",
             "help": "Glob patterns, * wildcard. Lines starting with # are comments. Empty = filter off.",
-            "multiline": true,
             "minRows": 6,
             "sm": 12
         },