pruneMessages no longer leaves orphaned tool-approval responses

Patch Changes

• f66ac32: fix(ai): prune orphaned tool-approval responses in pruneMessages

  When pruning a specific tool by name (toolCalls: [{ type, tools: [...] }]), pruneMessages left the tool's tool-approval-response in place while removing its tool-approval-request and tool-call. The tool name of an approval response was resolved per-message, but approval responses live in a separate tool message from their approval request, so the name could never be resolved and the response was always kept. Tool name resolution is now done across all messages, so approval requests and responses are pruned together.