fix: a V4 SETTLE of ETH paid from the router reads as moved from the sender (closes #682)

V4Router pays a SETTLE of ETH from the router's own ETH, whichever payer
it names. The router holds the transaction's value. So a SETTLE of ETH
that names the router as payer now counts as paid by the user.

When an earlier step left ETH in the router, such a SETTLE gets lines of
its own. Its line reads "Up to" and its amount, and that amount never
joins the Amount total. When the decoder does not know the SETTLE's
amount, as for CONTRACT_BALANCE, its line reads "Unknown (could not be
decoded)", also on the step that sets the input side.

One existing row in tests/uniswapRecipient.test.js now expects the ETH
lines. Its SETTLE spends all the router's ETH, the transaction's value
included.

Model: opus-5-5

README.md

@@ -3522,44 +3522,44 @@ Currently supported:
   none): one of a token other than `Token In`; one of `Token In` after an amount
   that is not a quantity (a V4 open delta, `ALREADY_PAID`, which keep their
   wording on the `Amount` line, or no stated amount, as of a V4 exact-out step);
-  one of `Token In` that ETH an earlier step left in the router may pay part of;
+  an ETH take whose line reads `Up to` (see above); and one whose amount the
-  and one whose amount the decoder does not know. When there is no `Amount`
+  decoder does not know. When there is no `Amount` line, each take the total
-  line, each take the total counts gets them too, so that every amount the
+  counts gets them too, so that every amount the decoder reads is shown: the
-  decoder reads is shown: the amount the step that sets the input side states,
+  amount the step that sets the input side states, when it is a quantity and the
-  when it is a quantity and the user pays that step (a V2 or V3 step whose
+  user pays that step (a V2 or V3 step whose `payerIsUser` is true, a V4 step
-  `payerIsUser` is true, a V4 step the user pays some of its input token, or a
+  the user pays some of its input token, or a `WRAP_ETH`, whose ETH comes from
-  `WRAP_ETH`, whose ETH comes from the transaction's value), and each later take
+  the transaction's value), and each later take of `Token In` added to it. A
-  of `Token In` added to it. A step that sets the input side gets none when the
+  step that sets the input side gets none when the user pays it none of its
-  user pays it none of its input token. A `PERMIT2_PERMIT` the decoder cannot
+  input token. A `PERMIT2_PERMIT` the decoder cannot read, then V3 exact-ins of
-  read, then V3 exact-ins of 600 USDT and 400 DAI paid by the user, give lines
+  600 USDT and 400 DAI paid by the user, give lines for both amounts. When the
-  for both amounts. When the step that sets the input side states no amount, the
+  step that sets the input side states no amount, the user pays it some of its
-  user pays it some of its input token, and there is no `Amount` line, that step
+  input token, and there is no `Amount` line, that step gets them too whenever
-  gets them too whenever another take's lines give a figure, or a
+  another take's lines give a figure, or a `PERMIT2_TRANSFER_FROM` of its token
-  `PERMIT2_TRANSFER_FROM` of its token gives one, on the lines below or, into
+  gives one, on the lines below or, into the router, on its `Paid to` line, so
-  the router, on its `Paid to` line, so that figure cannot read as all that
+  that figure cannot read as all that leaves. When it states no amount and the
-  leaves. When it states no amount and the user pays it none of its input token,
+  user pays it none of its input token, that step never gets them, with a permit
-  that step never gets them, with a permit or without. They come in step order,
+  or without. They come in step order, except that the step that sets the input
-  except that the step that sets the input side comes first when it has them,
+  side comes first when it has them, followed, when there is no `Amount` line,
-  followed, when there is no `Amount` line, by the other takes the total counts:
+  by the other takes the total counts: `Moved from the sender`, its amount,
-  `Moved from the sender`, its amount, worded as the `Amount` line words one, or
+  worded as the `Amount` line words one, or `Unknown (could not be decoded)`
-  `Unknown (could not be decoded)` when the decoder does not know it;
+  when the decoder does not know it; `Token moved`, giving the token's address
-  `Token moved`, giving the token's address as the `Token In` line does; and
+  as the `Token In` line does; and `Moved to`, which reads
-  `Moved to`, which reads `The swap step that spends it`. A token the decoder
+  `The swap step that spends it`. A token the decoder does not know gives the
-  does not know gives the `Moved from the sender` line alone. A step may also
+  `Moved from the sender` line alone. A step may also take from the user's
-  take from the user's wallet what the decoder did not read: a V4 step whose
+  wallet what the decoder did not read: a V4 step whose input or one of whose
-  input or one of whose `SETTLE`s or `SETTLE_ALL`s it cannot read, which the
+  `SETTLE`s or `SETTLE_ALL`s it cannot read, which the router still runs; a V2
-  router still runs; a V2 or V3 exact-in or exact-out step or a
+  or V3 exact-in or exact-out step or a `PERMIT2_TRANSFER_FROM` whose input it
-  `PERMIT2_TRANSFER_FROM` whose input it cannot read, such as a V3 step whose
+  cannot read, such as a V3 step whose path is shorter than one token address or
-  path is shorter than one token address or has bytes after its last hop; every
+  has bytes after its last hop; every `PERMIT2_TRANSFER_FROM_BATCH`; every
-  `PERMIT2_TRANSFER_FROM_BATCH`; every `EXECUTE_SUB_PLAN`, wherever it stands;
+  `EXECUTE_SUB_PLAN`, wherever it stands; and every step it fails on. Each such
-  and every step it fails on. Each such step gives one `Moved from the sender`
+  step gives one `Moved from the sender` line among those, reading
-  line among those, reading `Unknown (could not be decoded)`. That line, or any
+  `Unknown (could not be decoded)`. That line, or any line for a token the
-  line for a token the decoder does not know, leaves no `Amount` line, whose
+  decoder does not know, leaves no `Amount` line, whose figure might be too low,
-  figure might be too low, and such a step before a `PERMIT2_PERMIT` keeps the
+  and such a step before a `PERMIT2_PERMIT` keeps the permit's amount from
-  permit's amount from standing. Then each `PERMIT2_TRANSFER_FROM` but one into
+  standing. Then each `PERMIT2_TRANSFER_FROM` but one into the router, in step
-  the router, in step order, gives three lines: `Moved from the sender`, the
+  order, gives three lines: `Moved from the sender`, the amount it moves, for
-  amount it moves, for example `1000000.0000 USDT`; `Token moved`, giving the
+  example `1000000.0000 USDT`; `Token moved`, giving the token's address as the
-  token's address as the `Token In` line does; and `Moved to`, which reads
+  `Token In` line does; and `Moved to`, which reads
   `The V2 pair the next swap spends` for a hop and `The sender` for `address(1)`
   on every router but `UniversalRouterV1`, and otherwise gives the address. A
   move into the router needs none of them, because its `Paid to` line and