fix: typed data with a missing field or a bool that is not true or false is refused (closes #552)

ethers signs a bool field by whether its value is truthy, so the string
"false" was shown as false and signed as true, and a bool field left out
was shown as nothing and signed as false. The sign screen now refuses
typed data whose message leaves out a declared field, at any level of
nesting, or holds a bool that is not true or false: the error line names
the field and Sign is disabled. The background refuses a signature for it
too. Presence is an own-key test, so a field named like a built-in
property such as constructor is not found by accident. signedPrimaryType()
moves to the shared module so the background reads the message as the
same type.

Model: opus-5-5

README.md

@@ -2182,6 +2182,13 @@ view would leave a wallet one click from deletion.
     - Typed data that states no primary type, or one other than the type it
       would be signed as, or that cannot be read → shown with the error line
       saying so and "Sign" disabled; only "Reject" remains
+    - Typed data whose message leaves out a field its type declares, at any
+      level of nesting, or gives a `bool` field a value other than `true` or
+      `false` → shown with the error line naming the field and "Sign" disabled;
+      only "Reject" remains. ethers signs a `bool` by whether its value is
+      truthy, so the string `"false"` would be signed as true and a field left
+      out as false. The background refuses such a signature too and answers the
+      site with the same sentence
     - Typed data whose domain `chainId` names a chain other than the active
       network's → shown with the error line naming both chain ids and "Sign"
       disabled; only "Reject" remains. EIP-712 asks for this, because the