v0.13.1 concession management and record, clients update, version report

doc/todo.md

@@ -41,7 +41,8 @@ into phases that each ship and test on their own.
 | D3 | Where SAN/PGN is produced | **Decided: server-side Go** (R1), derived on read from the initial FEN and the UCI line: no schema change, one implementation for web and CLI, no third-party script under the CSP. |
 | D4 | Player names | **Done.** `white_name`/`black_name` snapshot the claimant's username in the claim transaction and survive renames and deletions; exposed as `players.*.name`. |
 | D5 | Draw rules | **Done.** Draws apply automatically after every move, as on most online servers: dead material, threefold repetition, and the fifty-move rule (FIDE's claimable draws, and so also its 75-move and fivefold rules). Draw offers (a computer answers from its evaluation) and resignation exist; the stored `termination` says how a game ended. |
-| D6 | Undo after a result | **Decided: keep allowed**, so a player can step back from a finished game and play a line again. Consequence: a finished game's stored history, result, and end time are rewritten by undo; replay shows the line as it stands now. |
+| D6 | Undo after a result | **Decided: keep allowed**, so a player can step back from a finished game and play a line again. Consequence: a finished game's stored history, result, and end time are rewritten by undo; replay shows the line as it stands now. **Refined (v3 schema):** a resignation or agreed draw between two humans is final, and undo, player changes, and unload respect other users' claims (no takebacks between players). Against the computer a concession can be undone, but the first one stays on record (`concession_*`) and in history and PGN. |
+| D8 | Human-vs-human in the web client | **Open.** The web client plays only against the computer; two-player games run through the API and terminal client (`join`, `poll`). A web mode would need join-by-link, a long-poll for the opponent's moves, and an offer indicator on the Draw button (accept by pressing it). |
 | D7 | List pagination | **Done.** Opaque keyset `cursor` on `(start_time_utc, game_id)`; `offset` kept for existing clients and exclusive with `cursor`. |
 
 ## Phase R1 — Notation Core (server) — done