fix: expand language IDs, fix AtCoder submit, normalize logging (#353)

## Problem

Language version coverage was incomplete across all platforms, AtCoder
submit used a stale cookie fast-path that caused silent failures, and
raw
`vim.notify` calls throughout the codebase produced inconsistent or
missing `[cp.nvim]:` prefixes.

## Solution

Remove cookie persistence from AtCoder login/submit (always fresh
login),
increase the submit nav timeout to 40s, and switch to in-memory buffer
upload with the correct per-language extension from a full
`_LANGUAGE_ID_EXTENSION`
map covering all 116 AtCoder languages. Expand `LANGUAGE_VERSIONS` in
`constants.lua` with all AtCoder languages, 15 new CF languages with
full
version variants, and 50+ Kattis languages. Fix AtCoder `prolog` ID
(`6079`→`6081`, was Pony) and remove the non-existent `racket` entry.
Replace all raw `vim.notify` calls with `logger.log`. Simplify the
submit
language doc to point at `constants.lua` rather than maintaining a
static table.

lua/cp/init.lua

@@ -21,7 +21,7 @@ local function ensure_initialized()
   local ok, result = pcall(config_module.setup, user_config)
   if not ok then
     local msg = tostring(result):gsub('^.+:%d+: ', '')
-    vim.notify(msg, vim.log.levels.ERROR)
+    logger.log(msg, { level = vim.log.levels.ERROR, override = true, sync = true })
     return false
   end
   config_module.set_current_config(result)