feat(aztec): upgrade to devnet 3.0.0-devnet.20251212

[mohammed7s]

Summary

• Upgrades Aztec dependencies from 3.0.0-devnet.2 to 3.0.0-devnet.20251212
• Applies breaking changes from Aztec migration notes
• Contract compiles successfully with new version

Changes

• Nargo.toml: Updated aztec and token dependencies to new version
• main.nr:
  • Storage/context now accessed via self (storage.x → self.storage.x)
  • External calls use self.call() instead of .call(&mut context)
  • Events now use #[event] macro inside contract block
• types/events.nr: Removed (events moved to main.nr as required by new macro)
• package.json: Updated all @aztec/* packages to new version
• Train.ts: Regenerated TypeScript bindings