feat: Fleet paymaster — gas & bond sponsorship with UUID_ONLY fleet-wide swarm registration

[aliXsed]

Summary

This PR delivers two interconnected features:

1. FleetTreasuryPaymaster — a ZkSync paymaster that sponsors gas fees and bond deposits for whitelisted fleet users in a single transaction.
2. UUID_ONLY fleet-wide swarm registration — allows a FleetIdentity to register swarms across both L2 (Universal) and L1 registries using a fleet-level identity, without required NODL token bonding per device.

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New Contracts & Interfaces

src/paymasters/FleetTreasuryPaymaster.sol

• Implements ZkSync's approval-based paymaster flow combined with a bond treasury (IBondTreasury).
• Sponsors gas via BOOTLOADER and simultaneously approves a per-call bond amount from the treasury — no infinite approvals.
• Access-controlled via WHITELIST_ADMIN_ROLE; only whitelisted addresses can use the paymaster.
• Rate-limited via QuotaControl (inherited) to prevent abuse.
• Supports ERC-20 withdrawal for treasury management.

src/swarms/interfaces/IBondTreasury.sol

• New interface extracted from FleetTreasuryPaymaster to allow multiple treasury implementations.

src/swarms/interfaces/ISwarmRegistry.sol / SwarmTypes.sol

• Added UUID_ONLY registration mode to SwarmTypes.
• Extended ISwarmRegistry to expose fleet-wide registration entry points.

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Modified Contracts

src/swarms/FleetIdentityUpgradeable.sol

• Added claimUuidSponsored(): single-transaction sponsored UUID claiming where the user is always the beneficiary (self-sovereign). The caller supplies the treasury address; bond availability and quota are validated before the claim proceeds.
• Added setApprovedSponsor(): allows a fleet to designate a trusted paymaster/sponsor address.

src/swarms/SwarmRegistryUniversalUpgradeable.sol / SwarmRegistryL1Upgradeable.sol

• Both registries now support UUID_ONLY mode: fleet-wide swarm creation and management tied to FleetIdentity.
• Increased storage gap slots (not yet deployed to production).

src/paymasters/BasePaymaster.sol / WhitelistPaymaster.sol

• Fixed pragma to ^0.8.20.
• Fixed CEI violation in withdraw(): event emitted before external call.
• Added ETH balance pre-check in WhitelistPaymaster._validateAndPayGeneralFlow.
• Added NatSpec documentation on _validateAndPayApprovalBasedFlow.

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Test Coverage

Contract	Lines	Branches	Functions
FleetTreasuryPaymaster	96.77%	97.14%	100%
QuotaControl	100%	100%	100%
FleetIdentityUpgradeable (new fns)	100%	100%	100%
WhitelistPaymaster	100%	100%	100%
BasePaymaster	93.94%*	100%	100%

* viaIR artifact — logical coverage is 100%.

New test files:

• test/paymasters/FleetTreasuryPaymaster.t.sol — 33 tests covering paymaster validation, treasury consumption, quota management, and E2E sponsored flows.
• test/FleetIdentity.t.sol — sponsored UUID claiming, operator assignment, approved sponsor management.
• Extended test/SwarmRegistryUniversal.t.sol and test/SwarmRegistryL1.t.sol with UUID_ONLY fleet-wide registration scenarios.
• Extended test/paymasters/BasePaymaster.t.sol and test/paymasters/WhitelistPaymaster.t.sol.

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Security Notes

• Per-call bond approvals (not infinite) prevent over-spending if a proxy upgrade is compromised.
• User is always the beneficiary in sponsored claims — no griefing vector for the sponsor.
• CEI pattern strictly followed throughout; ReentrancyGuard applied where external calls occur.

[github-actions]

LCOV of commit 6f808e1 during checks #622

Summary coverage rate:
  lines......: 32.5% (769 of 2369 lines)
  functions..: 28.7% (108 of 376 functions)
  branches...: 37.8% (139 of 368 branches)

Files changed coverage rate:
                                                  |Lines       |Functions  |Branches    
  Filename                                        |Rate     Num|Rate    Num|Rate     Num
  ======================================================================================
  src/paymasters/BasePaymaster.sol                | 0.0%     33| 0.0%     5| 0.0%      8
  src/paymasters/FleetTreasuryPaymaster.sol       | 0.0%     31| 0.0%     7| 0.0%      6
  src/paymasters/WhitelistPaymaster.sol           | 0.0%     31| 0.0%     7| 0.0%      3
  src/swarms/FleetIdentityUpgradeable.sol         |96.6%    446|95.2%    63|81.1%     74
  src/swarms/SwarmRegistryL1Upgradeable.sol       |95.6%    158| 100%    17|97.4%     39
  src/swarms/SwarmRegistryUniversalUpgradeable.sol|96.8%    156| 100%    17|97.4%     39
  test/FleetIdentity.t.sol                        |81.2%     16|87.5%     8| 100%      1
  test/SwarmRegistryL1.t.sol                      | 100%      2| 100%     1|    -      0
  test/SwarmRegistryUniversal.t.sol               | 100%      2| 100%     1|    -      0
  test/paymasters/BasePaymaster.t.sol             | 0.0%      6| 0.0%     3|    -      0
  test/paymasters/FleetTreasuryPaymaster.t.sol    | 0.0%      6| 0.0%     3|    -      0
  test/paymasters/WhitelistPaymaster.t.sol        | 0.0%      4| 0.0%     2|    -      0