Align Canton SDK packages and lift the dapp-sdk override

[gabitoesmiapodo]

User story / Problem statement

Currently the root overrides pins @canton-network/dapp-sdk to 1.1.0, silently blocking the 1.1→1.2 bump, and carpincho-wallet is on @types/node ^24 while the rest of the repo is on ^25. The Canton SDK family also trails by a minor.

Expected outcome

The Canton SDK packages are on their latest minor, the override no longer blocks the bump, and the @types/node split install is removed.

Acceptance criteria

• Lift or retarget the root @canton-network/dapp-sdk override
• @canton-network/dapp-sdk 1.1.0 → 1.2.0
• @canton-network/core-splice-provider 1.4.0 → 1.5.0
• @canton-network/core-types 1.4.0 → 1.5.0
• @canton-network/core-wallet-dapp-rpc-client 1.4.0 → 1.5.0
• Align carpincho-wallet @types/node ^24 → ^25
• npm install clean, lint + typecheck + tests pass

Technical notes

Part of #76. Treat as one SDK-family change because the override must move in lockstep with the bump.