fix: floor the persisted fields a restore dereferences, and make each field's floor an executable claim (closes #362)

A persisted container was checked while its ENTRIES were dereferenced
unchecked. A stored `{"0x…": "notalist"}` in allowedSites passes the state
gate, renders a working popup, and then throws inside saveState()'s per-
hostname merge, so every save from that moment on fails while the UI looks
entirely healthy. deniedSites has the identical shape; fraudContracts is the
same class with a milder consequence.

The sweep for that class found four more:

- selectedToken, dereferenced as text behind a truthiness-only restore gate.
- rpcUrl, handed whole to `new JsonRpcProvider()` by getProvider(), which
  throws SYNCHRONOUSLY for a non-string — from txStatus.js and addWallet.js,
  neither inside a try, and the first reachable from a stored
  `currentView: "wait-tx"` through the unguarded restoreView().
- The ENTRIES of viewData. Four restore branches gate on one truthy field and
  hand the rest to a renderer that calls address.toLowerCase(): a stored
  `{"currentView":"success-tx","viewData":{"hash":"0x1"}}` throws out of
  restoreView(), skipping the rest of popup init.
- selectedWallet / selectedAddress. `wallets` is a real Array, so a stored
  "map", "length", "constructor" or "__proto__" is TRUTHY: hasValidAddress()'s
  `&&` does not short-circuit and `.addresses[…]` throws. A stale INTEGER index
  is the safe case.

Floors, in src/shared/persistedState.js: allowedSites/deniedSites through
siteMap(), fraudContracts and each hostname list through textList(),
selectedToken and activeAddress as text-or-null, rpcUrl and blockscoutUrl as
non-empty text, selectedWallet and selectedAddress as a non-negative integer
or null, and each networkEndpoints pair's two URL fields — which
applyChainSwitchFields() assigns straight onto s.rpcUrl on the next switch.

Guards, in src/popup/viewRouter.js: the four restore branches that gate on one
truthy field now check the entries their renderer dereferences, as
txStatus.restoreWait() has always done for wait-tx. "confirm-tx" joins
ADDRESS_VIEWS, because its Sign button dereferences
state.wallets[state.selectedWallet] behind no guard of its own.

A stored own "__proto__" key is dropped by siteMap(): it can never be a wallet
address, so it grants nothing, and keeping it only keeps a value the next save
would hand to the prototype setter. networkEndpoints keeps unknown keys by
design, so mergeMapByKey() in src/shared/state.js now writes with
defineProperty as well — the guard in the floor was being undone one layer
downstream.

A save that fails is also told, not merely repaired: onSaveFailure() reports
every failed save, awaited or not (the save queue's own rejection handler is
what made a failure vanish), and the popup raises a persistent "NOT SAVED"
banner naming the reason. doRefreshAndRender() no longer rejects, since every
one of its call sites fires it and walks away.

The per-field justification in the header of src/shared/stateSchema.js is
replaced by tests/persistedFieldContract.test.js. That comment shipped a false
claim in three consecutive changes; the artifact was the problem. The test is
one row per persisted field, declaring the property that field's floor is
claimed to have and PROVING it by driving the real code with hostile values —
the gate for a field the gate refuses, normalizePersisted() for a field it
floors, the real JsonRpcProvider constructor for rpcUrl, and — for every field
whose only defence is that nothing dereferences it structurally — a boot of the
real popup entry point over that value onto EVERY view the popup can reopen
onto.

That last part is what makes the claim falsifiable, and it is why this defect
class is worth a harness at all: it lives on the RESTORE path and not on Home.
So the suite goes red on a field any restorable view dereferences on render, on
a field that gains a floor while its row still claims it has none, and on a
field added to PERSISTED_FIELDS with no row. What it does not reach is what no
stored record reaches by itself: a view only forward navigation opens, and
anything behind a click. The header and the README mirror now point at it
instead of restating it.

The boots are cheap enough to keep by construction rather than by sampling.
Every field the router itself reads is driven onto each view individually,
since a hostile value in one of those legitimately changes which view renders;
every other unfloored field is corrupted on the SAME boot, and that boot has to
land on the view it stored — so a field that does move the routing cannot hide
in the crowd, and the failure path re-boots one field at a time to name it.
That is thirty-three boots instead of six hundred; the suite runs in about 13s
against a 30s cap.

The DOM stub in tests/support/popupBoot.js gained one thing to make any of that
possible: an element's parentElement. Without it success-tx and transaction
threw on the first line that hides a field's wrapper, so neither renderer could
be booted onto at all — every boot aimed at them fell back to Home instead, and
the base profile the sweep starts from is now asserted to render each view
rather than fall back, so that cannot go unnoticed again.

tests/backNavigation.test.js

@@ -153,7 +153,7 @@ describe("Back onto a view the reopened popup never rendered", () => {
 
     test("Back onto the transaction detail renders it", () => {
         reopenedOn("settings", ["main", "transaction"], {
-            viewData: { tx: { hash: "0xdead" } },
+            viewData: { tx: { hash: "0xdead", from: ADDRESS, to: ADDRESS } },
         });
         goBack();
         expect(calls).toEqual(["transactionDetail"]);
@@ -162,7 +162,14 @@ describe("Back onto a view the reopened popup never rendered", () => {
 
     test("Back onto the transaction confirmation restores it", () => {
         reopenedOn("settings", ["main", "confirm-tx"], {
-            viewData: { pendingTx: { to: ADDRESS, amount: "1" } },
+            viewData: {
+                pendingTx: {
+                    token: "ETH",
+                    from: ADDRESS,
+                    to: ADDRESS,
+                    amount: "1",
+                },
+            },
         });
         goBack();
         expect(calls).toEqual(["confirmTx"]);
@@ -171,7 +178,7 @@ describe("Back onto a view the reopened popup never rendered", () => {
 
     test("Back onto the success screen renders it", () => {
         reopenedOn("settings", ["main", "success-tx"], {
-            viewData: { hash: "0xdead" },
+            viewData: { hash: "0xdead", to: ADDRESS },
         });
         goBack();
         expect(calls).toEqual(["successTx"]);
@@ -180,7 +187,7 @@ describe("Back onto a view the reopened popup never rendered", () => {
 
     test("Back onto the failure screen renders it", () => {
         reopenedOn("settings", ["main", "error-tx"], {
-            viewData: { message: "execution reverted" },
+            viewData: { message: "execution reverted", to: ADDRESS },
         });
         goBack();
         expect(calls).toEqual(["errorTx"]);