Add missing build resources

[SenNeonoveNoci]

• Moved agent-related resource logic into a dedicated AgentResource object for better clarity and separation of concerns.
• Agent configuration resources are now built independently and no longer rely on default resources. The previous approach had an unintended side effect: default resources were implicitly included without clear disclosure, which required adjustments to maintain expected behavior.
• Introduced a "build resources" category to better organize related metadata.
• Added device.manufacturer and os.description to the build resources for enhanced device and OS context.
• Added fallback for the app.version resource.
• Adjusted utilities/extensions for Application and Context