feat(frontend): add a terminal theme and three-way theme switcher

Adds the cyber theme to the console and login page, replaces the dark/light toggle with a theme switcher, and moves the login page script to /login.js so it is served under the existing CSP.

packages/frontend/src/lib/useTheme.ts

@@ -1,10 +1,10 @@
 import {useEffect, useState} from 'react'
 
-type Theme = 'dark' | 'light'
+export type Theme = 'dark' | 'light' | 'cyber'
 
 function getStored(): Theme {
     const v = localStorage.getItem('floci-theme')
-    return v === 'light' ? 'light' : 'dark'
+    return v === 'light' || v === 'cyber' ? v : 'dark'
 }
 
 export function useTheme() {
@@ -15,7 +15,5 @@ export function useTheme() {
         localStorage.setItem('floci-theme', theme)
     }, [theme])
 
-    const toggle = () => setTheme(t => t === 'dark' ? 'light' : 'dark')
-
-    return {theme, toggle}
+    return {theme, setTheme}
 }