chore(contracts): Move the contracts examples to a dedicated package

[SamarthJ2004]

What does this PR do?

This PR moves example contracts from contracts/src/examples/ to a dedicated examples/ package.
It updates import paths, sets up separate build & test configurations, and ensures example contracts are tested independently using Foundry & Hardhat.

Related ticket

Fixes #927

Type of change

• Chore
• Bug fix
• New feature
• Documentation update

Check list

• My contribution follows the project's guidelines
• I have made corresponding changes to the documentation
• Unit tests for any smart contract change
• Contracts and functions are documented

[cla-assistant]

All committers have signed the CLA.

[alainncls]

Hey @SamarthJ2004 can you just sign the CLA here? 🙏

[alainncls]

@SamarthJ2004 there is a small linting issue.
Can you run pnpm run prettier:fix at the root of the project and push the formatted file(s)?

[SamarthJ2004]

i ran prettier:write as :fix was not available
and pushed the changed files

[alainncls]

i ran prettier:write as :fix was not available and pushed the changed files

You're right, that's the correct command 😅
Everything is green, I'm merging your branch!
Thank you so much for your contribution to Verax! 🙏