feat: treat default allocation as unallocated in getTotalAllocation reporting

Modified getTotalAllocation() to exclude default allocation from reported
totals when the default target is address(0), since address(0) cannot
receive minting. This provides clearer reporting of actual allocated
issuance while maintaining the internal 100% allocation invariant.

- Updated getTotalAllocation() to check if default is address(0)
- When default is address(0), subtract default allocation from reported totalAllocationPPM and allocatorMintingPPM
- Internal 100% allocation invariant remains unchanged
- Updated 12 tests across 3 test files to expect new reporting behavior
- All 165 tests passing

Author: RembrandtK

packages/interfaces/contracts/issuance/allocate/IIssuanceAllocationAdministration.sol

@@ -72,6 +72,17 @@ interface IIssuanceAllocationAdministration {
      */
     function forceTargetNoChangeNotificationBlock(address target, uint256 blockNumber) external returns (uint256);
 
+    /**
+     * @notice Set the address that receives the default (unallocated) portion of issuance
+     * @param newAddress The new default allocation address (can be address(0))
+     * @return True if successful
+     * @dev The default allocation automatically receives the portion of issuance not allocated to other targets
+     * @dev This maintains the invariant that total allocation is always 100%
+     * @dev Reverts if attempting to set to an address that has a normal (non-default) allocation
+     * @dev No-op if setting to the same address
+     */
+    function setDefaultAllocationAddress(address newAddress) external returns (bool);
+
     /**
      * @notice Distribute any pending accumulated issuance to allocator-minting targets.
      * @return Block number up to which issuance has been distributed