### Task 3: Establish the V1 proxy, initialization, views, and administration

**Files:**
- Create: `src/BankV1.sol`
- Create: `test/helpers/BankTestBase.sol`
- Create: `test/BankV1Admin.t.sol`

**Interfaces:**
- Produces `initialize(address,address)`, `asset()`, `balanceOf(address)`, `totalLiabilities()`, `contractVersion()`, `pause()`, `unpause()`, and owner-authorized UUPS upgrades.
- Consumes `MockUSDC` and OpenZeppelin `Upgrades.deployUUPSProxy`.
- Freezes V1 application storage as `_asset`, `_balances`, `_totalLiabilities`, then `uint256[47] __gap`.

- [ ] Create `BankTestBase.sol` with deterministic `owner`, `alice`, `bob`, and `stranger` addresses from `makeAddr`; deploy `MockUSDC`; deploy the proxy with:

```solidity
proxy = Upgrades.deployUUPSProxy(
    "BankV1.sol:BankV1",
    abi.encodeCall(BankV1.initialize, (address(token), owner))
);
bank = BankV1(proxy);
```

All bank calls in tests target `proxy`; retain `implementation = Upgrades.getImplementationAddress(proxy)` only for assertions.

- [ ] Write failing admin tests for:

  - initialized asset, owner, unpaused state, zero liabilities, and version `1`;
  - initialization with zero asset;
  - initialization with zero owner through `OwnableInvalidOwner`;
  - proxy double initialization;
  - direct implementation initialization;
  - only owner can pause/unpause;
  - views still work while paused;
  - `_authorizeUpgrade` rejects a non-owner through `upgradeToAndCall`;
  - implementation `proxiableUUID()` is available directly while the proxy-context call reverts.

- [ ] Run the focused suite and observe red:

```bash
npm_config_offline=true forge test --match-path test/BankV1Admin.t.sol -vvv --force
```

Expected red: `BankV1` is missing.

- [ ] Implement the minimum V1 skeleton with these imports and inheritance order:

```solidity
import {Initializable} from "@openzeppelin/contracts/proxy/utils/Initializable.sol";
import {UUPSUpgradeable} from "@openzeppelin/contracts/proxy/utils/UUPSUpgradeable.sol";
import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import {OwnableUpgradeable} from "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import {PausableUpgradeable} from "@openzeppelin/contracts-upgradeable/utils/PausableUpgradeable.sol";

contract BankV1 is
    Initializable,
    UUPSUpgradeable,
    OwnableUpgradeable,
    PausableUpgradeable,
    ReentrancyGuard
{
    IERC20 internal _asset;
    mapping(address account => uint256 balance) internal _balances;
    uint256 internal _totalLiabilities;
    uint256[47] private __gap;
}
```

Use `error InvalidAsset(address asset);`. The initializer checks the asset before calling only `__Ownable_init(initialOwner)` and `__Pausable_init()`. `Initializable`, `UUPSUpgradeable`, and `ReentrancyGuard` are stateless/shared in pinned OpenZeppelin 5.6.1 and have no initializer calls.

- [ ] Add the only permitted validator annotation and no other bypass:

```solidity
/// @custom:oz-upgrades-unsafe-allow constructor
constructor() {
    _disableInitializers();
}
```

- [ ] Add `pause`/`unpause` with `onlyOwner`, simple views, `contractVersion() public pure virtual returns (uint256)`, and `_authorizeUpgrade(address) internal override onlyOwner {}`. Do not add deposits or withdrawals yet.

- [ ] Run green verification and inspect storage:

```bash
forge fmt
npm_config_offline=true forge test --match-path test/BankV1Admin.t.sol -vvv --force
forge inspect BankV1 storage-layout
```

Expected: tests pass and the application fields appear in the frozen order. OpenZeppelin namespaced/stateless internals must not be mistaken for permission to reorder application fields.

- [ ] Commit:

```bash
git add src/BankV1.sol test/helpers/BankTestBase.sol test/BankV1Admin.t.sol
git commit -m "feat: establish UUPS bank V1"
```

---