Extract the AI tool definition interfaces from the core debug module to the devtools primitives module. This relocates ToolDefinition, ToolGroup, and DevtoolsToolDiscoveryEvent to the primitives folder, exposing them cleanly via "export type" in the devtools entry point, improving module organization and readability.

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What kind of change does this PR introduce?

• Bugfix
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What is the current behavior?

These types are part of Angular Core.

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What is the new behavior?

These types are part of Angular Primitives.

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