Add username support for Battle.net

[TedTschopp]

Battle.net (Blizzard) username / BattleTag validation

Category: gaming

Goal: Explore whether Battle.net usernames or BattleTags can be reasonably validated for availability.

Notes:

• Battle.net identities are often more complex (BattleTag#1234) and may not map cleanly to a simple public profile URL.
• This issue is exploratory: document findings and implement a checker only if a stable, public endpoint can be used.

Suggested approach:

• Investigate any public web profiles or APIs for Battle.net players.
• If a reliable URL exists, implement a validator using the existing helper functions.

Implementation notes:

• Add gaming/battlenet.py.
• Implement validate_battlenet(username: str) or similar, documenting any caveats.