fix: replace deprecated vim.loop with vim.uv

Problem: vim.loop is deprecated since Neovim 0.10 in favour of vim.uv.
Five call sites across scraper.lua, setup.lua, utils.lua, and health.lua
still referenced the old alias.

Solution: replace every vim.loop reference with vim.uv directly.

lua/cp/health.lua

@@ -13,7 +13,7 @@ local function check()
     vim.health.error('cp.nvim requires Neovim 0.10.0+')
   end
 
-  local uname = vim.loop.os_uname()
+  local uname = vim.uv.os_uname()
   if uname.sysname == 'Windows_NT' then
     vim.health.error('Windows is not supported')
   end

lua/cp/scraper.lua

@@ -57,7 +57,7 @@ local function run_scraper(platform, subcommand, args, opts)
   env.CONDA_PREFIX = ''
 
   if opts and opts.ndjson then
-    local uv = vim.loop
+    local uv = vim.uv
     local stdout = uv.new_pipe(false)
     local stderr = uv.new_pipe(false)
     local buf = ''

lua/cp/setup.lua

@@ -179,7 +179,7 @@ function M.setup_contest(platform, contest_id, problem_id, language)
       contest_id = contest_id,
       language = lang,
       requested_problem_id = problem_id,
-      token = vim.loop.hrtime(),
+      token = vim.uv.hrtime(),
     })
 
     logger.log('Fetching contests problems...', vim.log.levels.INFO, true)

lua/cp/utils.lua

@@ -5,7 +5,7 @@ local logger = require('cp.log')
 local _nix_python = nil
 local _nix_discovered = false
 
-local uname = vim.loop.os_uname()
+local uname = vim.uv.os_uname()
 
 local _time_cached = false
 local _time_path = nil
@@ -336,7 +336,7 @@ function M.timeout_capability()
 end
 
 function M.cwd_executables()
-  local uv = vim.uv or vim.loop
+  local uv = vim.uv
   local req = uv.fs_scandir('.')
   if not req then
     return {}