fix: correct token association check

[AubreyDDD]

Description:

Corrects the token association verification logic in ·token_airdrop_transaction.py·. The previous implementation incorrectly displayed token balances (which are always 0 after association) instead of properly checking whether tokens were associated.

Related issue(s):

Fixes #815

Notes for reviewer:

Checklist

• Token association information is now correct
• Example still run successfully
• No other functional behaviour should be altered
• Add a changelog entry (see docs/sdk_developers/changelog_entry.md).
• Commit using verified GPG-signed commits

[Copilot]

Pull request overview

This PR fixes the token association verification logic in the token airdrop example. The previous implementation incorrectly displayed token balances (which are always 0 after association) instead of properly checking whether tokens were associated with an account.

Key Changes:

• Refactored the token association verification to check for token presence in token_balances dictionary rather than displaying balance values
• Updated the output format to clearly indicate whether tokens are "Associated" or "NOT Associated"
• Added a corresponding changelog entry documenting the fix

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
examples/tokens/token_airdrop_transaction.py	Corrects the logic to check if tokens exist in the token_balances dictionary instead of displaying misleading zero balance values
CHANGELOG.md	Documents the fix for token association verification in the changelog

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[exploreriii]

Request review if available @hiero-ledger/hiero-sdk-python-triage

[exploreriii]

Hi @AubreyDDD
We just need to improve the association check, but actual balance checks can be desirable to help the user understand how the airdrop actually moves tokens around

[exploreriii]

Thanks a lot @AubreyDDD and for your suggestion!