fix: a send the confirmation screen refuses moves nothing on it (closes #583)

Sign & Send wrote its refusals, a network changed since review and a gas limit or fee over its bound, into the errors box above the password field. That box reserves one empty line, so a refusal grew it and pushed the password field and Sign & Send down.

Each refusal now has its own box with its sentence fixed in index.html, holding its space from the first paint and only made visible, as #558 did for the balance messages. One sentence is true of all three bounds and quotes no number; the full reason is logged. A Chrome test raises the stub node's fee only at signing and checks nothing moved; a unit test refuses a gas limit over its bound into the same box.

Model: opus-5-5

README.md

@@ -430,6 +430,11 @@ reserve while sitting on the same side of the estimate, so swapping the two in
 what [#154](https://git.eeqj.de/sneak/AutistMask/issues/154) was, and it was
 previously correct by reading only.
 
+It also covers a send that Sign & Send refuses for its network fee: the stub
+node quotes an ordinary fee while the confirmation screen is drawn and one over
+the bound when Sign & Send asks again, and the refusal must broadcast nothing
+and leave the password field and Sign & Send where they were.
+
 It also covers both ways the wait for a sent transaction's receipt ends on the
 error screen: lookups that still find no receipt 60 seconds after the broadcast,
 and six lookups in a row that fail. Each must show its own message, and Done
@@ -1793,6 +1798,9 @@ view would leave a wallet one click from deletion.
       estimated, and it says the wallet does not know how many decimal places
       the token uses and that the transaction cannot be sent; for any other
       failure it asks the user to go back and try again
+    - Two more reserved error boxes, made visible when "Sign & Send" refuses a
+      send because the active network changed or because of its gas limit or fee
+      (see Transitions), so the refusal moves nothing
     - Password: an inline field on this screen, not a modal, with its own error
       line
     - "Sign & Send" button (disabled if errors, while the balance is being read,
@@ -1810,7 +1818,7 @@ view would leave a wallet one click from deletion.
     - "Sign & Send" after the active network was switched in Settings since this
       transaction was reviewed → nothing is signed; "The active network changed
       after this transaction was reviewed, so it was not sent. Please go back
-      and review it again." in the errors box, no screen change. After a switch,
+      and review it again." in its own box, no screen change. After a switch,
       "Back" from Settings draws this screen again from the saved transaction,
       as a popup reopened onto it does; when Send is beneath it on the stack, as
       when Send showed it in the same popup, "Back" lands below Send instead
@@ -1824,6 +1832,13 @@ view would leave a wallet one click from deletion.
       fee estimate and the contract and never-sent recipient checks ask that
       network's RPC endpoint, and the Etherscan label check asks that network's
       explorer
+    - "Sign & Send" (correct password) when the gas limit, a fee per gas or the
+      total fee the RPC endpoint fills in at signing is over its bound in
+      `assertWithinCeilings()` (`src/shared/approvalVerify.js`) → nothing is
+      signed; "The gas limit or fee the RPC endpoint quoted for this transaction
+      is more than this wallet will sign for, so it was not sent. Please go back
+      and try again." in its own box, the same sentence for all three, no screen
+      change
     - "Sign & Send" (wrong password) → "Wrong password." on the password error
       line, no screen change
     - "Sign & Send" signs as the From address above, not as whichever address is