Fix JSONDecodeError in link filters

[ruzaqiarkan-eng]

This PR fixes a JSONDecodeError that occurred in the backend when processing link_filters. The root cause was the use of single quotes in JSON strings within the contracts.py file, which is invalid according to JSON standards.

Key changes:

1. Data Correction: Converted all single-quoted link_filters in flexirule/ruleflow/core/contracts.py to use escaped double quotes.
2. Frontend Robustness:
   • Updated flexirule/public/js/flexirule/core/control_registry.js to fallback to an empty object if JSON.parse fails.
   • Updated flexirule/public/js/flexirule/rule_builder/components/rule_config/ActionSettings.vue to sanitize link_filters before returning them.
   • Updated flexirule/public/js/flexirule/rule_builder/stores/useMetaStore.js to sanitize filters before making the frappe.desk.search.search_link call.
3. Linting: Ran pre-commit run --all to ensure code quality and consistency.

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PR created automatically by Jules for task 17439329735015731471 started by @ruzaqiarkan-eng

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