fix(folio): author spec weights to match testing intent

Revert the account saturation gate: it starved newAccountBalanceIsZero
once it tripped, and a magic account count is app-state tuning, not
intent. Instead weight the generators by what the properties need:
the transaction chain leads, account creation stays exercised, and
doubleTaps gets explicit weight everywhere because double-submission
idempotency is what the spec is testing for.

examples/folio/sanderling/spec.ts

@@ -10,7 +10,7 @@ import {
   weighted,
   whenRoute,
 } from "@sanderling/spec";
-import { defaultActions } from "@sanderling/spec/defaults";
+import { defaultActions, doubleTaps } from "@sanderling/spec/defaults";
 import {
   computeHomeTotalBalance,
   parseTypedAmount,
@@ -134,15 +134,8 @@ const login = actions(() => {
 
 const accountNames = from(["Checking", "Savings", "Travel", "Emergency Fund", "Investments"]);
 
-// Saturation gate: a few accounts are enough to exercise every balance
-// property. Without the gate the short add-account loop (2-3 steps, back to
-// home) outcompetes the 5-step transaction chain at every re-draw and the
-// run fills with account creation instead of transactions.
-const ACCOUNTS_ENOUGH = 3;
-
 const addAccount = whenRoute(route, ["home", "add-account"], () => {
   if (route.current === "home") {
-    if (accounts.current.length >= ACCOUNTS_ENOUGH) return [];
     const btn = addAccountButton.current;
     return btn ? [Tap({ on: btn })] : [];
   }
@@ -181,11 +174,16 @@ export const properties = {
 
 export const setup = login;
 
-// Targeted depth (addAccount / addTxn) drives the deep flows; defaultActions
-// adds breadth so the fuzzer wanders the whole app and types edge-case values
-// into every field, stressing the balance invariants above.
+// Weights declare testing intent. The transaction chain is the focus: it is
+// the deepest flow and both balance properties observe it. Account creation
+// stays in the mix because newAccountBalanceIsZero needs fresh accounts to
+// fire. doubleTaps gets explicit weight on every screen because rapid
+// double-submission is a failure mode these forms must be idempotent under.
+// defaultActions adds breadth so the fuzzer wanders the whole app and types
+// edge-case values into every field.
 export const actionsRoot = weighted(
-  [50, addAccount],
-  [30, addTxn],
+  [25, addAccount],
+  [45, addTxn],
+  [10, doubleTaps],
   [20, defaultActions],
 );