fix: WebSocket /api/live silently dropped + atoms.tsx missing useRef/useEffect imports

Two compounding bugs from the previous comprehensive rewrite that
together produced "distance shows 0 + console useRef error":

1. Server-side route table overflow.
   esp_http_server cfg.max_uri_handlers was 32. The previous PRs added
   /api/mesh GET/POST, /api/topology GET/POST, /api/factory_reset,
   /api/ping, /api/system GET/POST, /api/radar/diag — bringing total
   route count to 33. The WS route is registered last, so it silently
   failed registration. No client could subscribe to live data, so the
   Live screen distance stayed at 0 forever. Bumped to 48.

   Verified post-flash: WS handshake returns 101 Switching Protocols
   from python ws client; chunked HTML still serves intact at 81 KB.

2. Client-side missing imports.
   atoms.tsx uses useRef (in DualHandleRange) and useEffect (in
   DualHandleRange + LineChart) but only imported useState from
   preact/hooks. Errors only fired on LEDs/Motion tabs where those
   components render. Added the missing imports.

Build: same 1.16 MB, both C3s flashed, all 11 endpoints verified live.

Author: Ravi Singh

firmware/components/webui/ui.html

@@ -1077,7 +1077,7 @@ esp_err_t webui_init(void) {
 
     httpd_config_t cfg = HTTPD_DEFAULT_CONFIG();
     cfg.lru_purge_enable = true;
-    cfg.max_uri_handlers = 32;
+    cfg.max_uri_handlers = 48;   /* was 32 — overflowed at 33 once mesh/topology/factory_reset/ping/system routes were added; the /api/live WS handler stopped registering and the dashboard could no longer get live data */
     cfg.max_open_sockets = 7;
     cfg.stack_size = 8192;
     cfg.recv_wait_timeout = 10;

firmware/components/webui/ui.html.gz

@@ -2,7 +2,7 @@
  * handoff (frontend/design-source/project/core.jsx). Kept in their own
  * file so they're easy to lift verbatim. */
 import { JSX } from 'preact';
-import { useState } from 'preact/hooks';
+import { useState, useEffect, useRef } from 'preact/hooks';
 
 export const Icon = ({ name, size = 16, stroke = 1.6, style }: {
   name: string; size?: number; stroke?: number; style?: any;