feat: one California is the product, not a flag

Behind `?one=1` the merged board was something a visitor could not find
and did not get: the site still landed on the Bay Area, the left column
still offered two other boards, and clicking one still tore the board
down and built another. The board existed and the product did not change.

A bare URL is now one California. `?city=sf` and `?city=socal` still get
the dedicated boards, unchanged and on purpose — twenty-nine capture
guards and the `bay-area` and `socal` budget cells aim at those boards by
name and assert the `data-board` they land on, and a metro id falling
back to the merged board would not degrade them, it would make them
silently measure something else. `?one=0` forces the old arrangement, and
both `california` budget cells now pass it: their caps are the plain
state board's 440,000, and without it they would measure the merged board
that `california-one` already covers.

Also `CALIFORNIA.md`: what a single cohesive California is still missing,
measured rather than listed. Every district on the board by the latitude
of its centre is 1 / 23 / 26 / 1 / 2 / 54 across 32-37 N and **zero above
38 N** — 107 districts, 103 of them in two clusters four hundred
kilometres apart, and four hundred and fifty kilometres of northern
California with not one building on it. Eight airports, all Bay or LA.
Two ports, both in San Pedro Bay. Two freeways of twelve vertices each
across a thousand kilometres of state.

The scale is not the problem and the file says so first: the board is
32.50-42.05 N and -124.50 to -114.00 W at 1,919 m to the unit, every
feature on its real coordinate, nothing schematic. It is not too small.
It is empty.

scripts/performance-budget.mjs

@@ -54,13 +54,23 @@ const SCENES = {
     // `california-overview` chapter never becomes ready — but a harness that
     // depends on an app default is a harness that reports someone else's change
     // as its own flake.
-    query: "?city=california&handover=0",
+    // `one=0` on purpose: both California cells' caps were measured against the
+    // **plain** state board, which is now what `?one=0` means and no longer what
+    // a bare `?city=california` gives. Without it these measure the merged
+    // board — which passes, and which `california-one` already covers, so the
+    // failure is two cells measuring one board and nobody watching the other.
+    query: "?city=california&one=0&handover=0",
     signature: "california-overview",
     ready: () => document.getElementById("boot")?.hidden === true && document.querySelector("#chapters .chapter[data-view='california-overview']") !== null,
   },
   "california-drive": {
     host: "tera.lumbridgecorp.com",
-    query: "?city=california&handover=0",
+    // `one=0` on purpose: both California cells' caps were measured against the
+    // **plain** state board, which is now what `?one=0` means and no longer what
+    // a bare `?city=california` gives. Without it these measure the merged
+    // board — which passes, and which `california-one` already covers, so the
+    // failure is two cells measuring one board and nobody watching the other.
+    query: "?city=california&one=0&handover=0",
     signature: "california-overview",
     ready: () => document.getElementById("boot")?.hidden === true && document.querySelector("#chapters .chapter[data-view='california-overview']") !== null && document.querySelector("#chapters .chapter[data-view='la-sf-us-101']") !== null,
     activate: () => {