Sign in on a phone with no console work, in the browser's own session

Mobile OAuth reused the desktop client all along; what stopped it was the
browser. Sending the user out to Safari or Chrome backgrounds the app, iOS
suspends it, and the redirect carrying the code arrives at a socket nobody
is accepting on. The consent page now opens in front of the app instead, in
SFSafariViewController or a Chrome Custom Tab, so the loopback listener
stays live and the existing `installed` client is enough. Verified against
Google's real consent screen on a simulator and an emulator.

A per-platform client is still supported and is now an upgrade rather than a
prerequisite. On iOS it buys ASWebAuthenticationSession, which shares
Safari's session so nobody is asked to sign in to Google twice. Android
needs nothing: Custom Tabs share Chrome's cookies, measured rather than
assumed. iOS session sharing could not be confirmed on the simulator and
wants a real device.

Never an app-owned WebView: Google blocks it, and rightly, since a webview
the app controls can read the password typed into it.

Cancelling is no longer reported as a failure. AuthEvent carries a
`cancelled` flag, set by comparing against the constant every back-out path
returns, and Google's `access_denied` on desktop counts too.

Five frontend bugs found by driving the real UI, not by reading it: the
details card slid under the tab bar leaving its buttons unhittable; the
ghost click after a touch pressed a button in the card that tap had just
opened, opening the editor by itself; the swipe that pages the day was dead
over every read-only block; 84px of macOS traffic-light lane was reserved on
platforms with no traffic lights; and the desktop header ignored the top
safe area on an iPad. A first launch now says what to do next rather than
showing an empty grid, and accounts are named as Google accounts throughout.

src/keys/commands.ts

@@ -176,7 +176,9 @@ const TABLE: Record<CommandId, Omit<Command, "id">> = {
     },
   },
   calendars: { label: "Calendars", palette: true, run: () => overlays().show("calendars") },
-  accounts: { label: "Accounts", palette: true, run: () => overlays().show("accounts") },
+  // Named for what it connects to rather than for the panel. "Accounts" on its own says nothing
+  // about whose, and this row is how somebody opening the app cold finds the thing to do first.
+  accounts: { label: "Google accounts", palette: true, run: () => overlays().show("accounts") },
   settings: { label: "Settings", palette: true, run: () => overlays().show("settings") },
   "toggle-theme": { label: "Toggle dark mode", palette: true, run: () => useTheme.getState().toggle() },
   "check-updates": {