🔒 fix: Unsafe JSON Parsing in Restore Command

[TrueAlpha-spiral]

🎯 What: The restoreCommand previously parsed checkpoint files from disk directly using JSON.parse and assumed the shape of the data without runtime validation, which could be a localized security risk if a checkpoint file is maliciously crafted or corrupted.

⚠️ Risk: While localized to the user's .gemini/checkpoints environment, parsing unsanitized JSON and directly reading arbitrary object properties (like history and toolCall.name) could lead to unexpected behavior, prototype pollution vectors, or unhandled exceptions crashing the application.

🛡️ Solution: Implemented robust schema validation using zod in packages/cli/src/ui/commands/restoreCommand.ts. The parsed data is now passed through toolCallDataSchema.parse() to ensure it strictly conforms to the expected structure before any data properties are accessed. Missing required properties (like toolCall) are caught gracefully and return an explicit error instead of causing unhandled runtime crashes. Tests in restoreCommand.test.ts have been updated to expect the safer, more explicit error handling.

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PR created automatically by Jules for task 2251652087094023051 started by @TrueAlpha-spiral

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