feat(teams): resolve team dividers by role ID instead of name

Divider placement matched the divider role by its exact Discord name, so
renaming the role in Discord silently broke positioning. Switch the
TEAM_DIVIDER_<SUFFIX> config to hold a role ID; resolve the ID to the
role's current name in apply_team_role_positions and keep the existing
name-based ordering maths downstream unchanged.

- config._parse_team_dividers now parses values as ints (rejects non-ints)
- resolve_divider / _team_divider cache / get_team_dividers return IDs
- apply_team_role_positions resolves each ID via guild.get_role once
- .env.example documents IDs and ships the CS2/LoL divider role IDs
- resolve_divider tests updated to assert IDs

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XPRsW4tazVtYi2jNzVQkre

.env.example

@@ -18,10 +18,11 @@ TEAM_SHEET_ID=
 # is matched against the section's title row in the sheet ("TipiLAN 2026 CS2
 # Registration Log") - every underscore-separated part must appear in it, so
 # CS2_2026 matches only the 2026 CS2 block while a plain CS2 would match any
-# year. The value is the EXACT Discord role name to place those teams under.
+# year. The value is the Discord role ID to place those teams under (matching by
+# ID means renaming the divider role never breaks positioning).
 # Optional: sections that match nothing still get their roles, just unpositioned.
-TEAM_DIVIDER_CS2_2026=
-TEAM_DIVIDER_LOL_2026=
+TEAM_DIVIDER_CS2_2026=1498736834656604251
+TEAM_DIVIDER_LOL_2026=1498736949706490017
 
 # Path to Google service account credentials JSON
 GOOGLE_CREDS_PATH=credentials.json