fix: restore deleted types and fix CI compile + format failures

[Chucks1093]

Closes #794

Several bad PR merges between #813 (governance) and #794 (snapshot/co-creator) deleted essential types and introduced duplicate definitions, breaking CI compilation and formatting.

Root causes fixed

Unclosed delimiter — buy_key_with_referrer circuit breaker block had wrong indentation (8-space instead of 12-space), causing the parser to treat the entire remainder of the function as the else branch of the let price = expression, leaving the impl block unclosed.

Deleted types (restored from pre-#794 history):

• StakingKey, StakePosition, StakingRewardsState, StakeExit, StakeRewardClaim, AuctionConfig structs
• DataKey variants: ProtocolFeeBps, LockupDurationSecs, HolderCapBps, StakePosition, StakingRewardsPool, CreatedAtLedger, LaunchPenaltyBps, QuorumBps, AuctionConfig, StakeUnlockLedger, TotalStaked
• ContractError variants: GlobalTradingHalted, FlashLoanDetected, FreezeQuantityExceedsBalance, and 6 others that were moved to StakingError but still referenced at call sites as ContractError::
• constants::storage helpers: auction_config, stake_unlock_ledger, total_staked
• AuctionPurchaseEvent and auction_purchase_topics in events.rs

Duplicate definitions removed:

• holder_cap_bps and last_buy_timestamp storage functions (each defined 2-3×)
• credit_staking_rewards_pool (kept the StakingRewardsState version, removed the old i128 version)
• FeeCollectedEvent, LockupBlockedEvent, duplicate event constants in events.rs

Format — ran cargo fmt --all to pass the CI format check.

[Chucks1093]

❌ CI Failed — verify (Contracts CI)

The verify check is still failing. Based on the PR title this is likely a compile error or format issue that wasn't fully resolved.

Likely causes:

• Remaining syntax errors or missing types after the restore
• cargo fmt not run before pushing — run cargo fmt --all and commit the result
• Unused imports or variables triggering deny(warnings)

Steps to fix:

1. Run cargo build locally and fix any compiler errors shown
2. Run cargo fmt --all to fix formatting
3. Run cargo clippy to catch any lint warnings treated as errors
4. Push the fixes — CI will re-run automatically