MCP server: option to redact personal data (PII) from MCP responses

Add a setting for the MCP server in Sleekplan: a toggle that, when enabled, automatically redacts personally identifiable information (end-user names, email addresses, etc.) in all data returned to MCP clients such as Claude. This lets teams use the MCP connector for triage, merging duplicates, roadmap and changelog work without customer PII being transferred to the AI provider. Raised in a support conversation by TaxCalc while evaluating the Claude connector.