feat(codechef): implement full CodeChef support (#354)

## Problem

CodeChef had no working login, submit, or contest list. The browser
selectors were wrong, the contest list was missing present/past
contests,
and problem/contest URLs were unset.

## Solution

Fix login and submit selectors for the Drupal-based site. Paginate
`/api/list/contests/past` to collect all 228 Starters, then expand each
parent contest into individual division entries (e.g. `START228 (Div.
4)`).
Add language IDs, correct `url`/`contest_url`/`standings_url` in
metadata,
and make `:CP <platform>` open the contest picker directly.

scrapers/language_ids.py

@@ -130,6 +130,14 @@ LANGUAGE_IDS = {
         "python": "PYTH 3",
         "java": "JAVA",
         "rust": "rust",
+        "c": "C",
+        "go": "GO",
+        "kotlin": "KTLN",
+        "javascript": "NODEJS",
+        "typescript": "TS",
+        "csharp": "C#",
+        "php": "PHP",
+        "r": "R",
     },
 }