refactor: declare escrow and ERC-20 events once

[zguesmi]

Non-breaking cleanup found while reviewing #345.

1. Dead network entry

scripts/verify.ts still listed 'dev-token' in skippedNetworks. That network was deleted from hardhat.config.ts in a6775e4, so the entry was dead.

2. Duplicate event declarations

Transfer, Reward, Seize, Lock and Unlock were each declared twice: in contracts/interfaces/IexecERC20.sol and in contracts/abstract/IexecEscrow.sol. It compiled only because the two declaration sites are inherited by disjoint contract sets (IexecEscrow -> IexecPoco1Facet, IexecPoco2Facet, IexecPocoBoostFacet; IexecERC20 -> IexecEscrowTokenFacet and the IexecInterfaceToken aggregate). Any contract that ended up inheriting both would have failed to compile.

Each event is now declared exactly once, in an interface (events are ABI, so an interface is the right home):

Interface	Events	Inherited by
IexecERC20Events	Transfer	IexecERC20, abstract IexecEscrow
IexecEscrowEvents	Lock, Unlock, Reward, Seize	abstract IexecEscrow, IexecEscrowToken

Approval stays in IexecERC20: only the ERC-20 entry points emit it.

3. Escrow events leave the ERC-20 surface

Reward, Seize, Lock and Unlock are escrow-accounting events. They are emitted from contracts/abstract/IexecEscrow.sol, contracts/facets/IexecPoco2Facet.sol and contracts/facets/IexecPocoBoostFacet.sol, never by ERC-20 code, so they no longer sit on IexecERC20.

They stay reachable from IexecInterfaceToken through the IexecEscrowToken interface, so the aggregate's flattened ABI does not change.

Two design notes

• Why Transfer moved to its own interface instead of staying inline in IexecERC20. The abstract IexecEscrow also emits Transfer, and it cannot inherit IexecERC20 (that interface has functions, and the concrete PoCo facets would then have to implement transfer, approve, ...). A shared events-only parent is the only way to declare the event once and keep it in every current ABI. Approval is deliberately not in that parent: adding it there would add an Approval event to the three PoCo facet ABIs, which do not have one today.
• IexecEscrowToken now declares four events it never emits. IexecEscrowTokenFacet carries Lock, Unlock, Reward and Seize in its published ABI today, inherited by accident from IexecERC20. Keeping the facet's ABI byte-identical requires preserving that. Dropping them from the escrow facet's ABI is a separate, breaking change.

Verification

ABI gate: abis/ snapshotted before the change, rebuilt, diffed. Only the two per-interface files that were supposed to move changed, plus the two new interface files:

M abis/contracts/interfaces/IexecERC20.json          events: [Approval, Lock, Reward, Seize, Transfer, Unlock] -> [Approval, Transfer]
M abis/contracts/interfaces/IexecEscrowToken.json    events: [] -> [Lock, Reward, Seize, Unlock]
+ abis/contracts/interfaces/IexecERC20Events.json
+ abis/contracts/interfaces/IexecEscrowEvents.json
(+ the mirrored human-readable-abis entries)

Every contract-level ABI is byte-identical: IexecEscrowTokenFacet, IexecInterfaceToken, IexecPoco1Facet, IexecPoco2Facet, IexecPocoBoostFacet and all other facets. ABI entries are sorted by solc, so the reshuffled inheritance does not move them.

topic0 is unchanged. No event signature was edited, only the declaration site, so every topic0 stays where it is and the subgraph is unaffected.

Runtime bytecode of IexecEscrowTokenFacet is identical up to the trailing CBOR metadata hash (first difference at byte offset 6566 of 6609, inside the metadata blob). The change is source-only; only the metadata hash moves.

Gate	Result
npm run build	compiled 119 Solidity files successfully
npm run check-storage-layout	pass, no output
npm run doc	regenerated, docs/solidity/index.md committed
npm run sol-to-uml	regenerated, 3 SVGs committed
npx tsc --noEmit	the 6 known pre-existing errors, no new ones
npm test	514 passing, 6 pending, 0 failing (same as base)
npm run format:check	All matched files use Prettier code style

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.54%. Comparing base (862c1f7) to head (2243d23).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #346   +/-   ##
=======================================
  Coverage   99.54%   99.54%           
=======================================
  Files          31       31           
  Lines        1095     1095           
  Branches      212      223   +11     
=======================================
  Hits         1090     1090           
  Misses          5        5           

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