Add bid wall optionality to launchpad v7

[pileks]

Make bid wall optional for launchpad v7 launches

Previously, every launch that raised more than 1.25x the minimum raise amount would automatically initialize a bid wall with the excess USDC. This PR makes the bid wall opt-in by adding a has_bid_wall flag to the Launch account, allowing launch creators to choose whether surplus funds go to the bid wall or the DAO treasury.

Changes

• New has_bid_wall field on Launch state -- set at initialization via InitializeLaunchArgs. When false, all post-LP USDC goes directly to the DAO treasury. When true, the existing bid wall allocation logic applies (excess above minimum_raise_amount funds the bid wall).
• **complete_launch conditional logic** -- the USDC split between treasury and bid wall now branches on has_bid_wall. With the flag off, usdc_to_bid_wall is always 0.
• Migration via resize_launch -- existing launches get has_bid_wall: false by default when resized, preserving backward compatibility. The OldLaunch struct is updated to include the accumulator_activation_delay_seconds field that was added in the prior release, and the resize handler now correctly preserves that value instead of zeroing it.
• SDK and event updates -- LaunchpadClient.initializeLaunchIx accepts hasBidWall, and LaunchInitializedEvent includes the new field.

SDK

New SDK version released under alpha tag (clients won't automatically pick it up):
https://www.npmjs.com/package/@metadaoproject/futarchy/v/0.7.2-alpha.0

Testing

Four new test cases in completeLaunch.test.ts cover the key scenarios:

1. hasBidWall: false with excess funding -- all post-LP USDC goes to treasury, no bid wall created
2. hasBidWall: true with funding above 1.25x minimum -- bid wall is initialized with the surplus
3. hasBidWall: true with funding at exactly the minimum -- no bid wall (insufficient surplus), same as before
4. hasBidWall: true with funding at exactly 1.25x minimum -- boundary case, no bid wall (LP allocation consumes the surplus)

All existing tests updated to pass hasBidWall (defaulting to false).