fix: resolve lua typecheck warnings in race and scraper

Problem: luals flagged undefined-field on uv timer methods because
race_state.timer was untyped, and undefined-field on env_extra/stdin
because they were missing from the run_scraper opts annotation.

Solution: hoist race_state.timer into a typed local before the nil
check so luals can narrow through it; add env_extra and stdin to the
opts inline type in run_scraper.

lua/cp/race.lua

@@ -114,12 +114,13 @@ function M.start(platform, contest_id, language)
 end
 
 function M.stop()
-  if not race_state.timer then
+  local timer = race_state.timer
+  if not timer then
     logger.log('No active race', vim.log.levels.WARN)
     return
   end
-  race_state.timer:stop()
-  race_state.timer:close()
+  timer:stop()
+  timer:close()
   race_state.timer = nil
   race_state.platform = nil
   race_state.contest_id = nil

lua/cp/scraper.lua

@@ -33,7 +33,7 @@ end
 ---@param platform string
 ---@param subcommand string
 ---@param args string[]
----@param opts { sync?: boolean, ndjson?: boolean, on_event?: fun(ev: table), on_exit?: fun(result: table) }
+---@param opts { sync?: boolean, ndjson?: boolean, on_event?: fun(ev: table), on_exit?: fun(result: table), env_extra?: table<string, string>, stdin?: string }
 local function run_scraper(platform, subcommand, args, opts)
   if not utils.setup_python_env() then
     local msg = 'no Python environment available (install uv or nix)'