Audit/fixes

[giorgilagidze]

Automated contract scans revealed 2 areas of the EscrowIVotesAdapter that, if misconfigured, could lead to incorrect state. This upgrade fixes the delegation checkpoint behaviour by overwriting delegation checkpoints, instead of appending them - preventing edge cases where binary search may return a stale value. It also removes approval-based delegation and undelegation flows, requiring that the msg.sender is always the owner of the tokenId, not an authorised caller. The latter path is not a useful feature in practice but could lead to incorrect state, so we have removed it. This set of transactions upgrades the contract without requiring a state change. No new state variables are introduced and no state variables are changed. Regression tests have been written to confirm this using OpenZeppelin Upgrades.

[github-actions]

LCOV of commit b3c9841 during Tests #1165

Summary coverage rate:
  lines......: 67.4% (2724 of 4044 lines)
  functions..: 70.8% (524 of 740 functions)
  branches...: 63.9% (163 of 255 branches)

Files changed coverage rate:
                                                        |Lines       |Functions  |Branches    
  Filename                                              |Rate     Num|Rate    Num|Rate     Num
  ============================================================================================
  src/delegation/EscrowIVotesAdapter.sol                |13.8%    210| 188%    24|    -      0