Continuation fixes

[pileks]

Futarchy

• Re-apply DAO's current seconds_per_proposal to proposal's duration_in_seconds at launch time (ensures updated durations take effect)
• Mark squads vault as writable signer in collect_meteora_damm_fees to match Squads SDK payer semantics
• Use wrapping_mul instead of saturating_mul for TWAP aggregator calculations and projections
• Remove #[event_cpi] from ExecuteSpendingLimitChange (no events emitted)
• Remove unused associated_token_program from StakeToProposal and UnstakeFromProposal
• Remove unnecessary mut from admin in AdminCancelProposal
• Update TWAP comment: max observation window is ~213 days, not ~208

Performance Package V2

• Replace ProposerType enum with direct proposer: Pubkey on ChangeRequest
• Add created_at_timestamp to PerformancePackage state (set on init)
• Add pp_created_at_timestamp to ChangeRequest to detect stale CRs after close/recreate
• Add staleness checks in execute_change: reject CRs whose pp_created_at_timestamp doesn't match the current PP, and reject CRs where proposer is no longer authority or recipient
• Add StaleChangeRequest error variant
• Add oracle check requiring at least one update_twap after twap_start_timestamp before reading
• Use wrapping_mul instead of saturating_mul in futarchy oracle aggregator projection
• Remove unused associated_token_program from CompleteUnlock
• Remove start_value from RewardFunction::CliffLinear - unnecessary due to cliff_value existing

Price-Based Performance Package

• Remove validation requiring min_unlock_timestamp to be in the future (allow init with past timestamp)
• Use wrapping_sub instead of saturating_sub for aggregator difference in complete_unlock
• Remove #[event_cpi] from BurnPerformancePackage (no events emitted)

V06 Launchpad

• Add has_one = launch constraint to funding_record in Claim and Refund
• Prevent initialization of launch with duplicate or empty spending limit members
• Fix time boundary: use require_gt! instead of require_gte! in Fund (strict expiry check)
• Remove unused launch_signer account from Fund
• Remove unnecessary mut from base_mint in Claim
• Remove unused system_program from Claim, Refund, and ReturnFunds

V07 Launchpad

• Add has_one = launch constraint to funding_record in Claim and Refund
• Remove unused launch_signer account from Fund
• Remove unnecessary mut from launch_signer in ClaimAdditionalTokenAllocation and InitializePerformancePackage
• Remove unnecessary mut from base_mint in Claim and ClaimAdditionalTokenAllocation
• Remove unused system_program from Claim and Refund

Bid Wall

• Remove unused payer account from CloseBidWall
• Remove unnecessary mut from user in SellTokens
• Remove unused system_program from CollectFees and SellTokens