[contracts] Add bet amount validation (min/max) in place_bet()

[Ehonrie]

Enforce min_bet_amount and max_bet_amount from ProtocolConfig inside place_bet() in contracts/market/src/lib.rs.

Add the validation gate before any token transfer occurs.

Acceptance Criteria:

• Bet below min_bet_amount panics with 'below minimum bet' error
• Bet above max_bet_amount panics with 'above maximum bet' error
• Bet exactly at min_bet_amount succeeds
• Bet exactly at max_bet_amount succeeds
• Unit tests cover all four boundary cases

[Nabeelahh]

@Nabeelahh has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer I have thoroughly read the description to this issue and I can resolve this according to the description required ensuring it meet all the acceptance criteria kindly assign.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Nabeelahh to this issue.

[Codekill33]

@Codekill33 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer, I'd like to work on this issue. I'll add min_bet_amount and max_bet_amount validation in place_bet() before token transfers occur, ensure appropriate errors are returned for out-of-range bets, and add unit tests covering all required boundary cases. ETA: 12 hours. Thank you.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Codekill33 to this issue.

[dinmacmd]

@dinmacmd has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi, I would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @dinmacmd to this issue.

[drips-wave]

Congratulations, @dinmacmd! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @dinmacmd: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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